The influence of the bionic leading edge tubercles on the aerodynamic performance of a high-speed low-pressure turbine has been numerically studied. Nine different tubercle configurations were designed to reduce the loss of the cascade at high Mach and low Reynolds numbers. Firstly, the effect of the geometric parameters of the bionic leading edge tubercles on the total pressure loss of the turbine cascade is discussed. Then, the flow control mechanism of the bionic leading edge tubercles is discussed. The results indicate that the total pressure loss of the turbine cascade could be reduced effectively by the leading edge tubercles. A larger tubercle size and larger amplitude-to-wavelength ratio can achieve a better loss reduction effect. The streamwise vortex generated by the leading edge tubercles continuously promotes the momentum exchange of the boundary layer in the process of downstream development, which makes the boundary layer shape plumper, and the ability to resist separation is enhanced. At the same time, the disturbance introduced by the streamwise vortex enables the separated boundary layer to transition quickly.