Simple lidar detecting wake profiles based on laser backscattering by wake bubbles at 180° is firstly introduced. Then the various noises of this simple lidar, including the background light, power frequency of 50Hz and its harmonics, radio frequency noise and inherent noise within the electronic system, are analyzed in detailed, and the relationship of the minimum detectable signal power and the echo signal power is discussed. Finally, under the condition of satisfying the noise level, the data processing method of wake profiles is given. For this method, the power spectral density estimation method is used to process the bubble laser scattering signal and cubic spline interpolation is used to obtain contour map of wake profile. The results show that the data processing method of wake profiles meets the noise level and the obtained contour map is reasonable.