The monitoring of the network transmission quality is more and more significant along with the improvement and popularity of IPTV. The most important work is to monitor packet loss among all the monitoring work. In this paper, we first introduce some related works which all assess video quality by monitoring the packet loss information. The packet loss information includes different frame types, various locations in the image and diverse distributions and so on. We focus on the distribution of lost packet, and conduct two subjective assessment experiments with different packet loss mode by designing diverse packet loss distribution. The goal of these experiments is to confirm that different distributions will cause a flow of the MOS value indeed under the condition of the same packet loss rate. And we analyze two subjective assessment results separately under the two modes. The work in this paper aims at improving the accuracy of current objective evaluation algorithms.