By analyzing the mechanical behavior of the turnout rails under train braking downhill with different slopes, the influence of slope on rail surface contact stress indicators are explored, which can provide useful reference for railway line designers to make decision on railway line slopes. Aiming at the 60AT rail at the heel end of the single turnout in the subway, the finite element method is used to carry out numerical simulation to establish the refined model of the subway axle and the 60AT rail. When the slope changes from 0% to 3.0%, most of the rail stress indicators change little, only the longitudinal shear stress of the rail surface and the rail surface friction change the most, where the changes are only 8.40% and 3.18% respectively, both of which do not exceed 10%.From the perspective of rail stress analysis, slope is not a decisive factor in controlling rail damage. In order to prevent excessive local stress on the rail surface during train braking, it is recommended to perform full-length quenching treatment on the surface of the rail in this section to improve the yield strength of rails.