Abstract: There is still a shortage of the experimental research of boundary layer transition in compressible flows nowadays due to the difficulty in measuring the turbulence intensity. Aiming at studying the influence of the turbulence intensity on supersonic boundary layer transition, a plate model is tested in a blow-down facility (FL–24y of China Aerodynamics Research and Development Center) at Mach 3. The turbulence intensity of the flow is changed by adjusting the arrangements in the stabilization section of the wind tunnel, which covers a range from 0.82% to 1.63%. The turbulence intensity is measured by interferometric Rayleigh scattering, while the boundary layer transition is derived by infrared thermography. The CFD simulation of the plate model transition is conducted based on the γ–Re_θ transition model. The results show that the transition onset position and transition end position obtained by the experiment and the simulation agree well, with the maximum relative error coefficient of 2% in the transition onset position and of 5% in the transition end position, which provides support to gain a deeper insight into the boundary layer transition mechanism in supersonic flows.