Abstract: Tomography particle image velocimetry (Tomo-PIV) is a laser speed measurement technique that obtains a three-dimensional velocity field in a space. Based on the Tomo-PIV imaging theory, this paper analyzes the relation between optics model of trace particle imaging and the three-dimensional discrete projection method of CT image reconstruction. A new synthetic images computing method which corresponds to the real wind tunnel's parameters are proposed. Then, a simulation laser illumination system with an irradiated volume of 80 mm×100 mm×100 mm is developed. The simulated Tomo-PIV images are obtained from the three-dimensional trace particles imaging model programmed by MATLAB. The factors affecting the imaging quality of PIV system are analyzed. Comparison of the synthetic images with the real particle images in which the number of particles per pixel is 0.007 7 shows the correctness of this simulation method.