The invention discloses a cascaded multi-ditch gate lockage discharge coefficient calibration method, and relates to the field of hydrodynamic parameter identification. The method comprises the steps of building a hydrodynamic simulating and forecasting model of a researching channel section; combining flow measured values and water level measured values of all gates in the researching channel section, and using a Kalman filtering assimilation algorithm to obtain a real-time analysis water level sequence; utilizing a Saint-Venant equation to deduce and obtain an analysis flow sequence of a ditch gamma according to the real-time analysis water level sequence of the gates of any ditch gamma in the researching channel section; deducing and obtaining a ditch gamma lockage discharge coefficient by utilizing the real-time analysis water level sequence of the gates of the ditch gamma and the analysis flow sequence of the ditch gamma. By means of the cascaded multi-ditch gate lockage discharge coefficient calibration method, the precision of the hydrodynamic simulating and forecasting model is sharply improved, and the accuracy of a forecasting value is improved.