For a certain type of aircraft landing gear design requirements, a dualchannel magnetic damper was designed. The dualchannel increased the viscous damping force when the MRF flowed through the annular gap and the adjustment range of the coulomb force, so the magnetic damper had a higher controllability. According to electromagnetic theory, the magnetic circuit was preliminary designed, and ANSYS was used to optimize the structure parameters further. The structure parameters which were most conducive to play the performance of the magnetic damper were got. The structure was more compact, the magnetic field distribution was more reasonable; comparison with the initial design, the magnetic field utilization increased more than doubled.