为了研究偏振光通过水体发生多次散射后偏振特性的变化，采用随机抽样拟合相函数的蒙特卡罗仿真方法进行模拟，通过模型仿真和实际实验来验证其真实性。仿真模拟了波长为532 nm的偏振光经过粒径满足（600±10） nm高斯分布的聚苯乙烯小球悬浮液的偏振态变化数据，模拟过程中的光子个数为10⁶。实验分别研究了0°线偏光、45°线偏光、左旋圆偏光以及右旋圆偏光在聚苯乙烯小球悬浮液中偏振态的变化情况。无论是仿真结果还是实验数据均表明，圆偏振光的偏振度下降幅度相比线偏振光要小20%，即聚苯乙烯小球悬浮液粒子密度数越高，偏振光的偏振度变化波动就越大，同时就保偏性来说，圆偏光优于线偏光。在相同浓度水体中，不同起偏角度的线偏光的偏振态变化差别不大。

In order to study the polarization characteristics of polarized light after multiple scattering through the water body， this paper uses random sampling to fit the phase function of Monte Carlo simulation method to simulate， through model simulation and actual experiments to verify its authenticity. The simulation simulates the polarization state change data of the polarized light with the wavelength of 532 nm through the suspension of polystyrene beads whose particle size satisfies the Gaussian distribution of （600±10） nm. The number of photons in the simulation process is 10⁶. In the experiment， the polarization states of 0° linear polarized light， 45° linear polarized light， left-handed circular polarized light， and right-handed circular polarized light in polystyrene pellet suspension were studied. Both the simulation results and the experimental data show that the degree of polarization decrease of circularly polarized light is at least 20% smaller than that of linearly polarized light. That is， the higher the density of polystyrene pellet suspension particles， the greater the fluctuation in the degree of polarization change，at the same time， the circular polarization is better than the linear polarization in terms of polarization preserving. In the same concentration of water， the polarization state of linearly polarized light with different polarization angles has little difference.