The present work aims to evaluate accurately the sealing performance of a rotary vane magnetorheological damper (RVMRD) in a wide range of temperature conditions. First, finite element simulation models were established for the static and dynamic sealing structures of the RVMRD based on the Mooney-Rivlin model. The deformation characteristics of the sealing constructions, including Von-Mises stress and contact pressure, were analyzed under different temperatures and hydraulic pressures using the AYSYS-Mechanical module. The static sealing simulation results indicate that the Von-Mises stress of the O-ring increases linearly with temperature. The maximum contact pressure results show that the static sealing structure can maintain good sealing performance under various working conditions. The dynamic sealing simulation results show that, under different medium pressures, the maximum Von-Mises stress of the dynamic sealing structure exhibits a nonlinear increase with temperature. In contrast, the maximum contact pressure at the rectangular slide remains almost linear with the temperature change. By analyzing the effective sealing width of the contact area between the rectangular slide and the rotor, the results show that the effective sealing width of the slip ring meets the requirements of the international standard ISO 3601: 2022 on the effective sealing width of rotary Glyd-rings for dynamic sealing under different working conditions, which further verifies that the dynamic sealing structure has good reliability.