Light detection and ranging (LiDAR) offers a method of remote wind speed measurement. A kind of all-fiber coherent Doppler lidar was proposed, whose components were connected via optical fibers. The simplicity of the structure is quite convenient for adjustment. First, the signal processing method used in this system was used to measure the simulated Doppler shift. The simulation results indicate that the more noise is added to the signal, the more errors will be obtained from the calculation. Second, the lidar system was utilized to measure the velocity of a hard target. The results conform very closely to the reference, whose absolute errors are less than 0.046 m/s. Finally, the lidar system was used to measure the speed of the water steam. The results deviate from the reference more than that of a hard target, whose maximum absolute error rises up to 0.925 m/s. The simulation and experiment results validate the accuracy and stability of the lidar system.