Abstract: In order to explore the effect of entropy layer on swept shock/turbulent boundary layer interaction, numerical simulation was applied to study a fin/blunt plate physical model. The results show that the thickness of the entropy layer upstream of the swept shock wave increases with the increase of the passivation radius at the leading edge of the plate, and the thickness of the boundary layer also increases with the increase of the thickness of the entropy layer. The introduction of the entropy layer does not change the quasi-conical similarity of swept shock/turbulent boundary layer interaction, nor does it change the position of VCO. It only changes the angle of upstream influence line and separation line. As the thickness of the entropy layer increases, the scales of the conical main vortex and the corner vortex formed by the swept shock/turbulent boundary layer interaction increase. The upstream entropy layer increases the total pressure loss in the downstream swept shock/turbulent boundary layer interaction region, but the relative total pressure loss caused by swept shock/turbulent boundary layer interaction is not affected by the upstream entropy layer.