Airborne LiDAR bathymetry is an active bathymetry method developed in recent years, which can quickly and efficiently obtain the water depth and underwater topography, especially plays an important role in surveying on shallow water and islandreefs where ships are not accessible. In general, the maximum detectable water depth of airborne LiDAR bathymetry systemis mainly affected by the turbidity of water. Therefore, a detailed study of water turbidity of the experimental regionin advance will contribute to design the experimental scheme. In this paper, taking the coastal waters of Hainan Island in South China as an example, we studied the relationship between turbidity of water and the bathymetry performance of an airborne LiDAR bathymetry system named CZMIL (coastal zone mapping and imaging LiDAR), and presented an algorithm that can estimate the spatial distribution of maximum CZMIL detectable water depth in the coastal waters of Hainan Island by using the values of diffuse attenuation coefficient of sea water. Firstly, we studied the Kd(490) inversion algorithm in the experimental water region. Secondly, the relationship between the diffuse attenuation coefficient Kd(490) and Kd(532) was established by using the measured optical profile data in this region. Then, the relationship between the diffuse attenuation coefficient Kd(532) and the maximum CZMIL detectable depth was summarized. Finally, the spatial distribution of Kd(532) and maximum CZMIL detectable depth in the coastal waters of Hainan Island were retrieved by using MODIS data. What’s more, the distribution of maximum CZMIL detectable depth in the coastal waters of Haikou City and Lingshui City are analyzed emphatically. The results provide a reference for the LiDAR bathymetric operation in the coastal waters of Hainan Island.