A transmission scheme of atmospheric laser communication based on depolarization ratio detection is proposed to solve the problem that the intersymbol interference in the communication link is caused by the multipath scattering effect in atmospheric laser communication. A Monte Carlo simulation is carried out by using the technologies of photon tracing and Stokes vector transform. The correspondence relationship between the depolarization ratio of received light and the optical depth of clouds is obtained through setting different physical depths and extinction coefficients of clouds. The relationship between the depolarization ratio of received light and the average pulse broadening time is obtained based on the Stotts formula. An optimal communication rate scheme under the multipath effect is proposed. This scheme can detect the depolarization ratio at the receiver of the laser communication system directly, evaluate the multipath intensity in atmospheric channel environment effectively, and achieve the largest communication transmission while ensuring the quality of laser communication. The research has theoretical guiding significance and application value in communication link optimization of satellite-ground laser communication and adaptive laser communication.