History matching of polymer flooding is exposed to problems such as the multiple parameters，heavy workload，and huge time consumption. Considering this，on the basis of the basic numerical simulation principle of polymer flooding and the research on the influencing factors in multi-parameter history matching，the widely used ENKF method was selected to explore the automatic history matching of polymer flooding. The nonlinear characteristics of the history matching parameters for polymer flooding were improved，and the automatic history matching software was developed by the ESMDA algorithm. Moreover，the history matching of polymer flooding was performed for an actual block. The results revealed that the multi-parameter mathematical model of polymer flooding can satisfactorily reflect the basic laws of polymer flooding in oil reservoirs. Upon the comprehensive adjustment to the parameters such as the polymer adsorption capacity，viscosity-concentration relationship，residual resistance coefficient，and inaccessible pore volume，the simulations are consistent with the actual performance of the reservoirs. In this way，the purpose of history matching is achieved. The constructed mathematical model for automatic history matching meets the algorithm requirements，and the developed automatic history matching software can reduce the systematic error of model calculations. The actual test results indicate that the water cut trend of the whole region basically conforms to the historical performance，and the cumulative oil production error of the whole region is 3.8%；the single well matching result is good，with a single well matching coincidence rate of 81.2%，which meet the requirement of history matching of polymer flooding.