The orifice of piston magnetorheological fluid shimmy damper directly affects output damping force.Based on experiments, the math model for damping force and AMESim hydraulic model of the MR damper with specific structure were established. Two models were verified by experiment to ensure the correctness. The establishment of models can provide theoretical basis for the design of piston MRF shimmy damper, to reduce design cycle and decrease research costs in the future.