Abstract: Currently,light detecting and ranging (LIDAR) systems are widely used in underwater object-detecting,ocean remote sensing,etc.However,the seawater and suspended granules do affect the transmission of laser,and restrict the application scope of LIDAR.The studies before almost aim at the reducing of backscattered component.However,the study on fore-scattered component bar ely appeared on literatures.The temporal and frequency characteristics of fore-scattered component of laser were studied and the theory about how to enhance the system SNR was presented.