When the air flow passes through the sweep plane of the wind turbine, the wake effect will be produced at the downstream of the wind turbine, which has different effects on the generation efficiency and fatigue load of the wind turbine. Based on coherent Doppler wind lidar, an all-weather wind field detection experiment was carried out in an offshore wind farm in Jiangsu Province. Due to the double Gaussian distribution of wind speed on the vertical section of the wind turbine wake, the traditional single Gaussian fitting algorithm has a large calculation error and can′t reflect the wind speed change law of real flow field near the wind turbine. An improved single-double Gaussian model fitting algorithm is proposed and used to analyze the wake width, velocity deficit and wake length of the target wind turbine. The feasibility and accuracy of the single-double Gaussian fitting algorithm for the fitting of the wake lateral wind speed are verified.