1. A body part detecting method comprising: identifying a group of sub-images relevant to a body part in an image to be detected; assigning, by way of a processor, a reliability coefficient for the body part to one or more of the sub-images in the group of sub-images based on a basic vision feature of the sub-images and an extension feature of the sub-images to neighboring regions; and detecting a location of the body part by overlaying sub-images having reliability coefficients higher than a threshold value.