The accuracy of measurement and detection probability of the sea surface using infrared laser in airborne laser bathymetry are discussed. The principle and analysis of the distance detection using infrared laser are introduced, and the accuracy of the inclined range at different scanning angles and different status of the sea, especially at different wind speed, is evaluated. Then the selection of discrimination threshold and the relationship between detection probability and SNR with giving criteria of detection probability are analyzed. Based on the simulation and parameters of the airborne laser bathymetry system, some improved methods of accurate measurement of inclined range are proposed.