The severe backscattering of the shallow seawater hinders the application of laser detection in the offshore. The backscattering of the echo signal restricts the depth, resolution and contrast of underwater target detection. Two novel ocean lidar with high scattering suppression radio, chaotic lidar and coherent dual frequency lidar, are studied. The two kinds of lidar signal owns the inherent intensity modulation characteristics, and then the backscattering owns the low frequency characteristics. Therefore, the backscattering of seawater can be removed by the band-pass or high pass filtering when the intensity of the object signal and the backscattering light are the approximate same magnitude, so as to improve the signal-to-noise ratio of the ocean lidar system.