The laser device is the core component of coherent Doppler wind lidar. The peak power and pulse width of laser transmitting pulse have important effects on SNR. Based on coherent Doppler wind pulse lidar, the peak power and pulse width influence on SNR is studied on the theoretical derivation and analysis, and the results show that the higher the peak power can realize the greater the signal-to-noise ratio of coherent Doppler wind lidar. But when the peak power is too large, the laser pulse may appear nonlinear phenomenon, which cause the damage of the laser. So the peak power must be less than the stimulated brillouin scattering power threshold. Increasing the pulse width can make the laser device to output more energy, but it will also make the spatial resolution lower, and the influence of turbulence on SNR will be greater. After a series of simulation analyses, it can be concluded that when the peak power is 650W and the pulse width is 340ns, the SNR of the system can be maximized. In addition, the coherent Doppler wind lidar system is set up to carry out corresponding experimental verification. The experimental results are consistent with the theoretical analysis and simulation, which verifies the correctness of the theoretical analysis and simulation results. It provides theoretical basis and practical experience for the design of laser transmitting pulse in coherent Doppler wind lidar system.