The applicability and accuracy of laser Doppler velocimeters(LDV) depend on the conditions in which the system operates:the characteristics of the surface measured,photoelectric detector,the environmental conditions,spectrum broadened,signal processing,etc.In this paper,based on a theoretic model of fringes and the principle of light interfering and scattering,a mathematic model of LDV for solid-state surfaces has been developed and we analyzed the relationship between the characteristics of the solid-state surface and the measurement accuracy for velocity through computer simulation in details,the results of experiment accord with the results of simulation exactly.The analysis leads to the conclusion that LDV system can measure precisely the speed of moving solid-state surface,and surface roughness is within the range depending on the measuring volume and fringe spacing.