Embodiments of the present invention provide a method, an apparatus, and a system for evaluating video quality. In the embodiments of the present invention, a method in the prior art that the video quality is determined only according to the number of lost packets and a packet loss rate is modified, and the location of the most important lost packet is determined by analyzing the influence of the lost packet on other packets, and a damage degree or degree of intactness of the video frame is determined according to the most important lost packets, so as to determine the quality of the video frame. The method greatly improves the precision for evaluating the video quality.