This article describes how with the development of cloud computing and virtualization technology, the desktop virtualization solution is becoming more and more mature. As a virtual desktop transport protocol, SPICE is used for deploying virtual desktops on servers and remote clients with high performance. However, it will take up a lot of network bandwidth and cause network congestion in a relatively poor network environment on video transmission. To solve this problem, a dynamic adjustment for video traffic (DCVS) in SPICE is proposed. It can dynamically adjust the bit rate of the video encoding according to the state of the virtual buffer and the feedback from client. The experiment results prove that DCVS can effectively reduce the video traffic and the probability of congestion.