How to Help a Dog Overcome Its Fear of Children
To help your dog overcome its fear of children, try to introduce it to quiet, calm children one at a time, so your dog knows what children are like. The earlier in your dog's life you can do this, the better. You can also walk your dog near parks or schools, which will help it gradually get used to being around children. If children are going to be near your dog, ask them to be calm and quiet, and explain that loud noises may frighten the dog. Also, you can create a safe space behind a safety gate or under a table, which can give your dog a place to go if it gets uncomfortable with loud children.
Socialize your dog. Introduce your dog to some quiet, calm children. Only let your dog interact with one child at a time at first. Ask each child to sit quietly so your dog can approach them. Praise your dog when it approaches the child and reward it for any positive interactions. Don't push your dog to interact with children at any stage during these introductions. This is especially effective when dogs are young, so they get used to children. Acclimate your dog to encountering children outdoors. Take walks near parks or schools where children are playing. Stay a safe distance away from areas with children at first. Gradually move closer to the areas with kids. If your dog doesn't exhibit any signs of fear, try sitting on a bench or the ground near playgrounds and letting your dog absorb the sounds of children playing and smell them. Reward your dog when it is calm and relaxed in an area near children at play. Watch your dog for signs of fear, including a lowered or tucked tail, laid-back ears, and a dropped head and neck. If you see signs that your dog is afraid, move it away from any nearby people or children. Tell children how to act around your dog. If children will be around your dog, ask them not to pay attention to your dog. Also, tell them to act quietly and calmly. Strongly discourage any screaming, yelling, running, or other loud noises. You should also ask children not to stare at your dog or make any quick movements. Show children how to safely give your dog treats. Encourage children who are helping socialize your dog to give it treats. Demonstrate giving treats with your hand down, palm up, fingers together. Tell children not to force any treats on the dog. Create a safe space for your dog in your home. Set up a safe space behind a safety gate, under a table, or in a bedroom. Or leave your dog's crate open so it can use the crate as a safe space. Make sure your dog can get to the space easily and quickly by removing any furniture or other barriers to its movement. Consider putting your dog in the space before children visit your home. Train your dog to go to its safe space. Stand near your dog's safe space and give it a verbal cue to move into the space, like “go to your spot.” Next, show your dog a treat and throw it into the space. Praise your dog when it moves into the space to eat the treat. Practice this sequence again a few times. Gradually train your dog to move into the space without the treat. Reward your dog with praise and occasionally give it treats to reinforce this behavior. Keep children away from the safe space. Tell children who visit your home to ignore your dog. Your dog will feel more secure without any pressure to interact or react to children. Don't allow children near this safe space. Be sure to supervise children in your home and keep them away from your dog's safe zone. Don't let children crowd your dog anywhere in your home. Teach your dog to hand target. Use this technique if your dog seems nervous around a child. It will help keep your dog's attention focused on you instead of on the child. Keep your palm flat and fingers together, then present your hand to your dog. Reward it by saying “good!” when it moves towards your palm. Give it a treat with your other hand when it touches your palm with its nose.  Practice this a few times until your dog masters the action. Steer your dog away from children. Don't reassure your dog if it demonstrates fear of a child -- this teaches it that it's fear is legitimate. Instead, move your dog away from a child that scares it. Walk with it into another room and interact positively so its focus shifts to you. Train your dog to move away. This teaches your dog it has the option of walking away from a child. Start by tossing a treat a few feet away from you, pointing to the treat, and telling your dog: “go away.” Repeat this sequence many times. Next, point and tell your dog to go away without tossing the treat. When your dog starts moving away, praise it by saying “yes!” or “good dog!” and tossing the treat. Never let a child follow your dog when it moves away to get distance from the child. Stop children who rapidly approach your dog. Get out of their way if you can. You might even hold up a hand and say “stop!” to protect your dog from children it doesn't want to meet. Don't punish your dog for being afraid of the children. It might start associating its punishment with the children it fears. 
Socialize your dog. Acclimate your dog to encountering children outdoors. Tell children how to act around your dog. Show children how to safely give your dog treats. Create a safe space for your dog in your home. Train your dog to go to its safe space. Keep children away from the safe space. Teach your dog to hand target. Steer your dog away from children. Train your dog to move away. Stop children who rapidly approach your dog. 