In order to investigate the effect of purge flow on the flow characteristics in the high-pressure turbine stator passage,the turbulence model SST was used to solve the three-dimensional unsteady Reynolds equation.The pressure fluctuations and airflow changes in the vane gas path were analyzed for the seal without seal cavity,the seal without seal air flow and the seals of four kinds of seal flow.The results show that purge flow injection of the front seal cavity is greatly affected by the pressure field of the upstream vane.Gas ingestion occurs in the high pressure area formed by the intersection of the pressure side and the suction side near the trailing edge of the vane.The purge flow injection occurs in the low pressure area affected by the suction side diffuser area at the middle position of the vane passage.The new vortex structure formed by mixing the purge flow with the main flow entrains part of the boundary layer fluid and weakens the strength of the secondary flow structure.At the same time,a blockage effect is formed on the main flow path,which promotes the secondary flow of the hub to the suction surface and the radial position is raised.The mixing of the purge flow and the main flow caused by the disc pump effect enhances the unsteady effect,and the increase of the purge flow can suppress the unsteady effect in the passage.