Abstract: Using the ERA-interim reanalysis data of the European Centre and through the calculation of Okubo Weiss (OW) parameter, the process of the formation of plateau vortex induced by the last plateau shear line on the Qinghai Tibet Plateau is analyzed diagnostically. The results show that: (1) The negative belt of OW can indicate the possible generation area of plateau shear line. When the OW value approaches 0, the shear line becomes unstable and the strength decreases gradually. The positive area of OW can indicate the subsequent movement trend and development of the plateau vortex, and the convergence area of air flow has a good corresponding relationship with the positive area of OW. (2) The air flow activity of the plateau shear line is mainly tensile deformation. In the generation stage of shear line, the air flow near the shear line makes tensile deformation movement. In the mature stage of shear line, the air flow tensile deformation reaches the strongest point. In the weakening stage of shear line, the tensile deformation movement of air flow weakens. (3) The generation and movement of shear line are mainly affected by the local variation term of the total deformation equation. The generating position and subsequent movement path of the vortex have a good correspondence with the divergence term of the horizontal vorticity equation. The convergence of air flow plays a major role in the primary stage of plateau vortex, and the weakening of convergence intensity will inhibit the eastward movement and development of plateau vortex.