To improve the accuracy and stability of the calculation of numerical simulation software for microbial enhanced oil recovery，we introduced a new model equation for microbial migration that reflects the influence of inaccessible pore volume，adsorption，and screening effect on the distribution of microorganisms in the reservoirs based on the previous experimental results on the migration and retention of microorganisms. Then，a one-dimensional，two-phase（oil and gas），and three-component（microorganisms，nutrients，and metabolites）mathematical model for microbial enhanced oil recovery was constructed. Through programming，the process of microbial enhanced oil recovery was simulated for the sensitivity analysis of inaccessible pore volume，adsorption，and screening effect. Consequently，the model could simulate the process of microbial enhanced oil recovery which is sensitive to inaccessible pore volume，adsorption，and screening effect. These parameters could be introduced for the accurate prediction of microbial concentration distribution，water cut，and recovery，offering a numerical simulation method to the preparation of construction schemes for microbial enhanced oil recovery.