As the most closely related layer with human, the planetary boundary layer’s height directly reflects the state of the atmosphere near the ground. Now the lidar has become the most effective tool to observe the planetary boundary layer, but the retrieval of the planetary boundary layer height from a large number of measured data limited its application. Four kinds of commonly used methods, such as the gradient method, standard deviation method, fitting method and wavelet covariance transform method, are introduced and analyzed, with the continuously measured data of polarization-Raman-Mie scattering lidar. The results show that the four methods have their own advantages and disadvantages. The gradient method, the standard deviation method and the wavelet covariance transform method are similar and accurate in data process, but not stable. The fitting method has good stability, but its derivation is not so accurate relative to the three methods above. All in all, the fitting method is better to be used to process a large number of data.