There is a new type of hydraulic accumulator has been presented in this paper, and for the magnetorheological fluid(MRF) chamber of the new hydraulic accumulator, the modeling and the solving method for the fluid-solid interactions and magnetic- fluid interactions in the MRF chamber are provided and also studied by the finite element method. And also, using the ADINA software, the finite element network model of the MRF chamber has been established while ensuring the consistency between the simulation model and the physical model as far as possible. And as a result, the pressure and velocity characteristics, alone with the magnetic field distribution of the flow field in the MRF chamber can be obtained in uncontrolled or power-on state. In the end, experiment has been done to verify the performance of the MRF, which lays the foundation for the optimization of the MRF chamber.