In the complex model structure and motion environment, it is basically impossible to obtain the unsteady aerodynamic load distribution on the surface by traditional methods. PSP technology is a new technology for measuring the surface pressure of wind tunnel model. Based on the phenomenon that the fluorescence intensity of luminescent coating molecules changes with pressure under the irradiation of excitation light with a specific wavelength, the pressure is converted into light intensity information, and then the image processing is carried out to calculate and obtain the surface pressure distribution of the model. This article introduces the measures to improve the measurement accuracy of the PSP system in low-speed wind tunnel, including the improvement of excitation light source, the development of spraying device, the optimization of image registration and so on. The test results show that the maximum standard deviation is 44.19Pa, and the merging sample standard deviation is 28.7Pa, the technique achieves the low speed wind tunnel engineering application levels.