The invention discloses a method for predicting recoverable reserves and evaluating a development effect of a gas drive reservoir. The method comprises: starting from an oil-gas two-phase seepage law,based on an exponential function relationship of gas-oil relative permeability, through a material balance equation and a Darcy law, deducing and establishing a novel gas-drive characteristic curve relation between the gas-oil ratio and accumulated oil under the condition of stable seepage of a gas-drive development oil field, reducing use of uncertain parameters, and providing a reliable oil reservoir engineering method for calculation of recoverable reserves in the middle and later periods of gas-drive oil field development; furthermore, drawing a gas-drive oil reservoir development effectevaluation chart through gas-drive characteristic curve derivation, the chart visually describing the internal relation among the gas-oil ratio, the recovery degree and the recovery ratio, and providing a basis for evaluation of the effects of oil field measures, comprehensive adjustment and the like.