The nonlinear dynamic characteristics of landing gear shimmy were studied and active control of shimmy were studied. According to bifurcation theories, the Hopf point and the shimmy limit-cycle amplitude by solving the nonlinear shimmy differential equations with numerical continuation. The stability of the limit-cycle was determined by calculating Lyapunov exponent. On this basis, the active control was used to suppress the shimmy and the appropriate mathematical model was constructed. And the nonlinear shimmy differential equations were solved after active control was applied. The results show that the active control strategy of landing gear can fully suppress the shimmy in airp;ane taxiing speed range by choosing proper control parameters, and has good robustness against varying system parameters.