Abstract: By means of Monte Carlo simulation of the process that photon transferring in the water,the depolarization of the polarized laser beam in the ocean is studied,as well as the effect of different ocean optical properties.The depolarization of different sea depth is obtained.The result shows that seawater with lots of particles playes great part in the depolarization of the polarized laser beam.When the polarized laser transmittes some distance under seawater,it will turn into depolarized laser.The particles with difference size distributed in the seawater are the main reason of the depolarization of seawater.The ocean optical property has great effect on the depolarization of seawater.As the increasing of the ocean attenuation coefficient,the transferring distance at which polarized laser turnes into depolarized laser is decreasing.