Abstract: In order to enhance the effect of MEOR,physical simulation of effect of operation parameters on MEOR were carried out.Four factor and three level orthogonal testing design,injection mode,injection volume,shut-in time and displacement rate after well reopen were set in three levels in microbial flooding experiments.The flooding experiment was conducted in the order of injecting microbes and shut-in for a period of time after water flooding followed by crude oil driving from using bacteria solution.Subsequently,the effect of various factors at different levels on oil recovery ratio in microbial flooding was evaluated to determine the optimal level of each factor.The results show that the effect of MEOR is optimal when 1:1 slug(inorganic medium and activated bacterial solution),injected volume of 0.6 PV,shut-in for two days,flooding speed at 3 PV/h at well reopening were used.This optimal combination increased oil recovery by nearly 32% after water flooding recovery ratio reaching 95%.This indicates the operation parameters such as microbial injection modes have a significant impact on the MEOR effect,so improved MEOR effect can be achieved through optimization.In order to achieve optimal results in practical treatment,these operation parameters should be optimized before implementation.