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; transmitting the facial image having a highest total degree of similarity: judging whether any calculated total degree of similarity exceeds a predetermined degree; when any calculated total degree of similarity exceeds the predetermined degree, going to the step of transmitting the facial image having the highest total degree of similarity; and when no calculated total degree of similarity exceeds the predetermined degree, decomposing each current facial image into a plurality of feature areas each associated with a measured degree of similarity, composing a new facial image using the feature areas having the highest total degree of similarity, and transmitting the composed facial image.