在激光雷达的水下应用中，由于水体对光的吸收和散射作用使得激光在水下的传输复杂多变，尤其是后向散射所造成的噪声会降低目标对比度甚至淹没目标回波，导致水下激光回波检测面临挑战。副载波调制技术可以有效地改善激光雷达系统水下探测性能，提高目标回波信号的信噪比。基于Monte Carlo方法提出了改进的副载波调制脉冲激光雷达水下传输模型，研究了海水衰减系数和通频带等因素对于系统性能的影响。仿真结果表明：相比于传统激光雷达，水体环境参数、滤波过程中的通频带选择对于系统水下探测性能影响较大；副载波调制技术可以提高目标回波信噪比和测量精度，有效改善系统性能。

In the underwater application of lidar, the underwater transmission of laser light is complicated and variable due to the absorption and scattering of light by water, especially the noise caused by backscattering will reduce the contrast of the target, and the target echo even will be drown, resulting in big challenges of water downward laser echo detection. The subcarrier modulation technology can effectively improve the underwater detection performance of the lidar system and increase the signal-to-noise ratio of the target echo signal. Based on the Monte Carlo method, an improved underwater transmission model of a subcarrier-modulated pulsed lidar was proposed. The effects of seawater attenuation coefficient and passband on system performance were studied. Simulation results show that compared with traditional lidar, the environmental parameters of the water body and the selection of the passband during filtering have a greater impact on the underwater detection performance of the system; the subcarrier modulation technology can improve the target signal-to-noise ratio and measurement accuracy, it effectively improve the system performance.