Abstract: In order to analyze the error of the velocity of sound in atmosphere, based on Brillouin lidar, the measuring method of sound velocity in atmosphere was put forward for its high precision, high speed and real time. The concrete relation between the velocity of sound and other atmosphere parameters was analyzed. Then, the measurement error of the velocity of sound was calculated and the numerical analysis was fulfilled. The results show that, in the condition of standard atmosphere, the precision of the velocity of sound is less than 0.269m/s in the height of 0km～86km. The Brillouin frequency shift has a greater influence on the error of the velocity of sound than the refractive index and the laser wavelength in the atmosphere. This analysis is a significant guide for the lidar design.