This paper is concerned with the Hopf bifurcation control of a brushless DC motor system. Firstly, the Hopf bifurcation style of original system is studied by limit cycle curvature coefficient; Then the washout filter is used to realize the Hopf bifurcation control of original system, and the required parameter condition that will change the Hopf bifurcation position of original system is given based on the Hopf bifurcation theory, besides the Normal Form of Hopf bifurcation is obtained based on the Normal Form method, and the Hopf bifurcation style is discussed by the real part of Normal Form, the required parameter condition that will change the Hopf bifurcation style is given; And the computer simulations(by Matlab software)are applied to illustrate the theoretical results, simulation figures and theoretical results reveal that the linear gain can change the position of Hopf bifurcation and even make the Hopf bifurcation eliminate, while the nonlinear gain can change the stability of limit cycles or to control the amplitudes of oscillations. The result above may be help for the practical application of brushless DC motor system.