We established the simultaneous equations of state variables by means of stepwise regression and basing on the historical materials of hydrology, meteorology and fishery statistical figures, as a useful tool for calculation of the effects of the Three Gorges Project on Changjiang River Estuarine fishery resources On the assumption that Three Gorges Project had been built and 180m design conducted the hydrology data can be drawn up according to the design. Using this tool and the simulant data the impacts of the Three Gorge Project on the fishery resources of Changjiang River Estuary are analysed. The results indicate that, upon the whole, the construction of the Three Gorges Project will have no harmful effects on the estuarine fisheris. The draft 180m design can raise CPUE by 0.0171 t/f per year in the Changjiang River Estuary fishery resources.