Using spaceborne platform for underwater laser detection has many advantages, including a large coverage area, high detection efficiency, good mobility, good concealment, and fast information transmission, however its implementation is difficulty greatly. In order to detect the target information reflecting the characteristics effectively, laser pulse signal needs to be through space channel, atmospheric channel, and water channel, and that is all bidirectional transmission, the link is very complicated. Through the establishment of laser transmission model and analysis of the link energy loss, the theory feasibility of spaceborne underwater lasertarget detection is verified.