Abstract1 This paper deals with the microbial enhanced oil recovery method. It covers: Mechanism of microbial influence on the reservoir was analysed;The main groups of metabolites affected by the hydrodynamic characteristics of the reservoir were determined;The criterions of use of microbial influence method on the reservoir are defined. The mathematical model of microbial influence on the reservoir was made on this basis. The injection of molasse water solution with Clostridium bacteries into the mixed type of rock was used in this model. And the results of calculations were compared with experimental data.