1. A facial expression recognition method, comprising: receiving a first facial image and a second facial image; calculating an expression feature of optical flow field between the first facial image and the second facial image corresponding to each of a plurality of expression information respectively; and determining a facial expression corresponding to the first and second facial images according to the calculated expression feature of optical flow field for each of the plurality of expression information and a plurality of the expression features of optical flow field in a facial database, wherein the facial database comprises the plurality of expression information and the plurality of expression features of optical flow field, and wherein each of the expression features of optical flow field corresponds to one of the plurality of expression information.