The invention provides a high-speed rail body locating system which comprises a fixed locating and measuring unit, a robot tail end measuring unit, a robot unit and an upper computer. The robot unit comprises robot bodies, a robot control cabinet and robot guide rails. The robot control cabinet is connected with the robot bodies. The two robot guide rails are arranged in parallel in the manner ofbeing spaced by a distance. Each robot guide rail is provided with one robot body. The robot bodies are connected with the robot tail end measuring unit through mechanical arms. Two rail body guide rails parallel to the robot guide rails are arranged on the inner sides of the two robot guide rails and used for bearing a rail body. The fixed locating and measuring unit is installed on the front side of the rail body stay position. The fixed locating and measuring unit is used for locating the position of the rail body in the length direction of the rail body guide rails. The invention further provides a high-speed rail body measuring method correspondingly. The system solves the problem of locating and measuring the rail body.