Effects of rim seal flow through uniform slot seal and contoured slot seal configurations on the turbine performance were investigated numerically. The results show that the gas ingress and egress structures are affected by stator disc

rotor disc and the tangential velocity in mainstream

and the rotating speed is less than that of rotor disc with the same direction. As a result

the flow patterns of rotor are changed

which strengthened the pressure side horseshoe vortex

thereby resulting in large changes of flow field of rotor exit. The interaction of seal flow and upstream vane weak induces the entropy rise in the rotor passages

leading to decrease of the turbine efficiency. Compared with uniform slot seal configuration

the contoured slot seal configuration collapses the big ingress and egress structures into smaller ones

and then has less negative effects on the turbine performance. The turbine efficiency is improved by 0.9%. The results prove that the contoured slot seal configuration has better turbine performance as well as better seal effectiveness.