1. A facial expression recognition method, comprising: generating a gray image according to an original image; outputting a face edge detection result according to the gray image; generating a motion skin extraction result according to the original image and generating a face and background division result according to the motion skin extraction result; outputting a face contour according to the gray image, the face edge detection result and the face and background division result; and outputting a facial expression recognition result according to the face contour; wherein the step of outputting the facial expression recognition result comprises: outputting a first feature vector according to the face contour; storing a plurality of designated facial expression images and a plurality of non-designated facial expression images, and outputting at least one second feature vector according to the designated facial expression images and the non-designated facial expression images; and outputting the facial expression recognition result according to the first feature vector and the second feature vector; and wherein the step of outputting the first feature vector comprises: outputting feature point data according to the face contour and the gray image; selecting a feature region according to the feature point data; and dividing the feature region into a plurality of equal portions and calculating an average gray value of each of the equal portions to output the first feature vector.