Due to the limitation of the structural strength of the ship compartment of the Three Gorges ship lift and the prevention of the ship touching bottom,the tonnage of ship passing through the ship lift cannot exceed 3,000 tons.At present,there is no corresponding fast calibration method for ship’s tonnage in the industry.We analyze the relation of different ship types of three-dimension with tonnage,take the ship square coefficient as the key point,and obtain an empirical formula for fast calculation of ship’s tonnage.Moreover,we propose a method for calibrating the tonnage of ships passing through the Three Gorges Dem after verifying the formula by an example.The results show that the accuracy of empirical formula of ship’s tonnage satisfies the requirements,and the proposed calibration method is fast and accurate.