Aiming at the characteristics of initial trajectory of underwater high-speed target after coming out of water,a measurement method is proposed for synchronous observing with electro-optical compound device to guide the laser rangefinder and high-speed camera.A measurement device is designed,and the design requirements of each device that meet the general measurement requirements are analyzed,and the feasibility of the scheme is demonstrated.The trajectory measurement accuracy of the device is preliminarily estimated.The results show that it can meet the measurement requirements,which provides an important means for short-range measurement and live observation for initial trajectory of high-speed target out of water,and has great military application value.