Abstract: In order to research the influence factors of laser coherent noise in high speed photography, and reduce the impact brought by speckle noise on the quality of high-speed photography imaging, the relationship between the roughness of the surface irradiated by the laser and the statistical properties of the laser speckle was studied. Based on the principle of Fresnel-Kirchhoff diffraction theory, the laser speckle patterns by reflection on random surface by Gaussian beam incident was analyzed, and the relationship between the SNR and autocorrelation and probability density function and the roughness of the incident surface was obtained through the statistics of a large amount of data of laser speckles. The results show that bigger roughness lead to smaller SNR of speckle field, degree of coherence and probability density, that is to say, the noise of the speckle increases with the increase of the roughness of the surface.