Numerical experiments show that on the northeastern edge of the Qinghai-Xizang Plateau the formation and movement of a vortex is closely related to topography and the activities of high-and low-level systems. After the removal of topography, the vortex would no longer exist. When the low-level subtropical high is powerful in intensity, the southerly wind prevails all through the eastern part of the plateau and its northeastern part is within the divergence field of the upper-air jet stream with vortex easily occurring. The factor of the non-adiabatic change can weaken the upper trough and make the vortex stagnant.