In order to quantitatively and qualitatively study the effect of formation rhythm，concentration of foaming agent and gas liquid ratio on oil displacement efficiency during nitrogen foam flooding process in bottom water reservoir，the bottom water reservoir model was established by CMG numerical simulation software，and the test scheme was separately designed according to the design principle of Box-Behnken Design（BBD）center combination in response surface methodology and single factor analysis. The mathematical regression model between the factors and the increment of oil recovery was established，and the degree of influence of all factors on recovery increment and their effect were clarified. In addition，the factors were optimized. The results show that the mathematical regression model has a good fitting effect on the experimental data and the effects sequence from large to small is formation rhythm，foaming agent concentration and gas liquid ratio.Under the experimental conditions of positive rhythm formation，6% of concentration of foaming agent and 1∶2-1∶1 of the gas liquid ratio，the recovery increment is higher. Quantitative and qualitative study on the influence of various factors on the recovery increment has great significance to deeply understand the mechanism of nitrogen foam flooding for EOR in similar bottom water reservoirs.