Abstract: In order to further improve the forecast accuracy of liquid production variation,the calculation formula for annual liquid production was derived with different production parameters.Based on mathematical models for fixed oil production or production decline at a certain speed,combined with conventional A and C water flooding performance curves,liquid production under different production parameters can be calculated by simultaneous solution.Taking a water flood development block in Daqing Oilfield as an example,the derived formula of liquid production was verified with different production parameters of this block,and the annual liquid production of this block was calculated.The results show that the formula of liquid production can meet engineering requirement,and the best rate of decline for crude oil production should be 3% in light of liquid production capacity in the block.According to liquid production under different production parameters obtained from the liquid production formula,combined with the liquid production capacity of the oilfield or block and production history,the best production parameters for this oilfield can be selected.