In order to meet the sealing requirements of the gas in the azimuth axis of the beam director,an outer cylinder separated magnetorheological fluid (MRF) sealing structure was designed,which is mainly composed of MRF,pole shoe,permanent magnet,outer cylinder and inner cylinder.The simplified model of the sealing structure was established by Maxwell,and the magnetic induction intensity and the distribution of the sealing structure were simulated.The influence of pole tooth shape on pressure resistance in MRF sealing structure was analyzed.It is concluded that when the seal gap is from 0.12 mm to 0.22 mm,the sealing performance of MRF with unilateral chamfer tooth shape is better.The orthogonal test method was used to optimize the tooth shape parameters such as sealing gap,tooth width,tooth height,groove width and unilateral chamfer.The orthogonal test results show that the sealing gap has the greatest influence on the pressure resistance value of magnetorheological fluid seal,followed by the pole tooth width,the groove width,unilateral chamfer and tooth height have a small impact on the pressure resistance value.Finally,a set of optimal parameters was obtained,and the sealing performance of the optimized magnetorheological fluid seal was improved by 199.4%.