In order to further study the aerodynamic characteristics of wrap-around fin at supersonic speed, numerical simulation of flowfield over wrap-around fin was done by FLUENT software at small angle of attack at supersonic speeds in this paper. Laminar model was adopted in computational model with the third MUSCL scheme. The numerical simulation was performed at small angles of attack from 0 degree to 8 degree, with Mach number from 2.5 to 5.5. Results have shown the complicated flow structure of wrap-around fin, such as shock wave, surface pressure distribution. Possible sources of lift of wrap-around fin at zero angle of attack were analyzed. And the change trends of lift and drag with mach number and angle of attack were analyzed.