In the design, development, and data inversion of spaceborne lidar, the forward model is critical. This study establishes a forward model for observing clouds and aerosols using spaceborne lidar. It can simulate ice clouds and aerosols, as well as other complex scenes. The model as a whole is made up of 8 sub-modules. The simulation results in the 532-nm channel show that in the deep convection scenarios, the clouds are deep and the signal attenuation is serious, thus, only the distribution of the cloud top can be distinguished. The influence of cloud microphysical characteristics on the effective detection of aerosols must be considered in the ice cloud and aerosol scenes. In terms of parameter sensitivity analysis, the relationship between telescope diameter, satellite orbit altitude, laser single pulse energy, and the signal-to-noise ratio can help with instrument design. The comparison of the attenuation backscattering coefficient calculated by the forward model with the actual detection results of CALIOP/CALIPSO shows a good consistency in the structure of spatial distribution. However, owing to the uncertainty in the CALIPSO inversion algorithm and the difference in parameter settings between the inversion and the forward model, some minor differences at different altitudes when comparing the average of all profiles remain.