Theoretical analysis shows that splitting ratio of signal paths affects the accuracy of wind speed measurement in dual edge Rayleigh wind measurement technology. Therefore, the splitting error should be calculated when evaluating the wind speed error, and one suitable spectroscopic instrument should be selected as much as possible. Multimode optical fiber beamsplitter and beamsplitter are usually used in lidar. As for beamsplitter, its splitting ratio is affected by the depolarization of the atmosphere. As for the multimode optical fiber beamsplitter, its splitting ratio is affected by the measurement error. According to the analysis, the range of relative beamsplitter change is from 0.07% to 0.63% due to depolarization effects in pure molecular scattering environment. However, the mean value of multimode optical fiber beamsplitter is 1.018, and the standard deviation is 0.4%. Therefore, multimode optical fiber beamsplitter is used in lidar. Finally, the Rayleigh Doppler lidar combined with balloon wind test, the test results show the wind field in good agreement.