Abstract: In order to explore the detection of obscure targets by means of lidar, the effects of obscure targets on returned lidar waveforms were studied. By using the method of mathematical modeling, the model of lidar waveforms returned from obscure targets was constructed, in which the effects of pulse stretch, spectrum reflectivity and depolarization on return waveforms were considered. The simulation data of the waveforms returned from obscure targets were obtained based on this model. The simulation data indicate that the reflectivity and depolarization of different targets has the prominent effect on return lidar waveforms, provide a foundation for future study on the detection of the obscure target based on return lidar waveforms.