1. A method for video instant messaging, comprising: picking up information in front of a display panel from different directions to capture a plurality of facial images; extracting a plurality of groups of current characteristic vectors from the facial images respectively; measuring a plurality of degrees of similarity each associated with an extracted current characteristic vector using a group of reference characteristic vectors; calculating a plurality of total degrees of similarity each associated with a facial image using the measured degrees of similarity; and transmitting the facial image having a highest total degree of similarity.