Abstract: Landing gear of aircraft is the key component to ensure safety during the process of takeoff and landing. This paper analyzes the dynamic characteristics of the landing gear system. Because of the inclusion of MR fluid, the landing gear damper system becomes a nonlinear system. In order to study the characteristics of the system, this paper builds the mathematical model of the landing gear damper by linearizing the nonlinear system. Based on the model, the frequency response of aircraft body displacement, aircraft body acceleration, landing gear displacement, and tire dynamic loading of the landing gear are analyzed. And the time-domain response of random road excitations is also analyzed. These analyses would be helpful in structure designing of the landing gear with MR damper and the advanced control of the damper system.