Abstract: Tomographic Particle Image Velocimetry(Tomo-PIV) is a kind of instantaneous velocity measurement technology combined PIV and computer tomography (CT), which can quantitatively obtain the three-dimensional structure of the flow field. It is successfully applied in the subsonic, transonic and supersonic wind tunnel and the supercritical airfoil verification experiment about riblets drag reduction was carried out. The layout of body light and camera is designed based on the situation of FD-12 wind tunnel in China Academy of Aerospace Aerodynamics. The free flow field under the condition of Ma=0.6 is measured by solving the problem of the uniformity diffusion of tracer particle, and compared with the test results of PIV. The data of both accord well, verifying the accuracy of Tomo-PIV. Meanwhile, the three dimensional velocity field in the rear of trailing edge is measured by attaching the smooth film and symmetrical riblets film respectively which used supercritical airfoil OAT15a as the carrier. The results reveal that the Mach number of the measurement field increases after attaching the riblets film. It shows that the riblets film can reduce the friction resistance of the wing and has certain drag reduction effect.