To choose the optimal estimating method to evaluate micro-Doppler characteristic of target, the research on the Cramer-Rao Bounds(CRBs), which was used to evaluate the performance of the estimating method, was indispensable. The closed form of CRBs for lidar signals with Gaussian noise was derived strictly in this paper. The relationships between the CRBs and factors including the target position, the length of processing data and SNR were analyzed. The simulation results indicate that decreasing the azimuth angle and pitch angle or increasing the data length and SNR can minish the CRBs of estimated parameters, while, the lower bounds are insensitive to the information of the noise variance. The mean square error of two frequently used estimators for micro-Doppler parameters were simulated and compared with the CRBs. In the end, the meaning of the strict derivation of CRBs in this paper was presented by comparing with the result got from approximate process.