In order to study the influence of the front and back plate structures on the pressure and flow field of the brush seal,the nonlinear Darcian porous medium model was used to establish the brush seal solution models of six different front and back plate structures.The rationality of the model was verified by comparing with the relevant experimental data.The pressure and flow field of the brush seals of six different front and back plate structures were numerically analyzed by ANSYS software.The results show that pressure ratio and plate structure play a key role in the sealing performance of brush seals.The leakage of brush seals increases with the increase of pressure ratio.The long front plate structure can reduce the leakage,and there is no difference in leakage between the basic and annular cavity back plate structures,while the through cavity back plate structure can significantly increase the leakage.The long front plate structure can reduce the pressure in the brush tow,and the back plate structure plays a decisive role in the pressure distribution of the brush seal.The through cavity back plate can eliminate some radial pressure gradient and improve the life of the brush seal.