In order to study the spatial distribution of maximum CZMIL (Coastal Zone Mapping and Imaging LiDAR) detectable depth in the northern South China sea, we firstly research the existing Kd(490) inversion algorithm in the northern South China Sea. The relationship between the diffuse attenuation coefficient Kd(490) and Kd(532) is established based on the optical profile data measured, and the relationship between the diffuse attenuation coefficient Kd(532) and the maximum CZMIL detectable depth is summarized. Then, using the remote measurement data of the Aqua-MODIS, we obtain the spatial distribution of diffuse attenuation coefficient at 532nmin the northern South China sea in January, June and October, 2014. It shows that June is more suitable for bathymetry operation than in October and January. Finally, we obtain the spatial distribution of maximum CZMIL detectable depth in June in the northern South China sea. The results show that the CZMIL detectable water depths in the northern South China sea are about 0-71.18 meters. The study provides a reference for the time selection and flight scheme of LiDAR bathymetry operation in the northern South China sea.