1. A pedestrian detection system, comprising: a camera module, mounted in a vehicle, configured to capture image around the vehicle; a process module, having two feature capturing modules that capturing gradient of granule features of the image, and converting the image to a histogram of gradient of granule feature (HOGG) feature comprising: dividing the image to a plurality of granules; obtaining a magnitude average value of each granule; obtaining a magnitude average difference value in diagonal orientation of the each granule in the plurality of cells; wherein each feature capturing module adopts histogram of oriented gradients and histogram of gradient of granule feature to capture features of the image; and a classifier that receives and analyzes the image for classifying the HOGG feature to determine whether having a pedestrian in the image.