Aiming at the saturation drift error occurring in the identification method of the constant ratio timing which is commonly used in laser fuze, an identification method of the composite moment between the front edge discrimination and the constant ratio timing and its error compensation model are proposed. The drift error model for the identification of the constant ratio timing is established and the variation law of the saturation drift error with the theoretical peak voltage of echo signals is analyzed. The compensation method of drift errors based on the composite moment identification method is proposed, and a mathematical model for compensating drift errors in the identification of the composite moment is established. The modified pulsed laser ranging formula is obtained and the verification experiment of the measurement precision is carried out. The results show that, the system errors can be effectively reduced by the composite moment identification and the error compensation correction methods and the ranging precision can be controlled within ±0.3 m or less.