Three kinds of labyrinth seals with rectangular boundary element,the rectangular groove type,front raised rectangular type,and post raised rectangular type labyrinth seals were designed by modifying the stator boundary of the straightthrough labyrinth seal.The leakage characteristics of labyrinth seals under different pressure ratio and rotating speed were studied.The axial pressure drop,velocity field,turbulent energy dissipation rate and streamlines were analyzed,and the flow mechanism of the seal were discussed.The results indicate that the pressure ratio has a great influence on the sealing performance of labyrinth seal,and with the increase of pressure ratio,the leakage of labyrinth seal is increased gradually.While the rotating speed has little influence on the sealing performance of labyrinth seal.The rectangular convex structure has lower leakage,and its leakage is less sensitive to the change of pressure ratio,so it can work stably in a wider range of pressure ratio.The front rectangular convex structure has the best sealing effect.The rectangular structure on the stator can destroy the boundary of the gas flow,strengthen the turbulent effect,increase the dissipation of turbulent kinetic energy,and effectively reduce the leakage.