Aiming at the problem of brake noise of drum brake, the principle of complex modal analysis is summarized, the finite element model is established, and the brake noise is predicted. The effects of brake pressure, brake drum angular speed, friction coefficient, young modulus and friction lining’s thickness on brake stability are analyzed comprehensively. The analysis results of effect factors indicate that: the friction lining’s young modulus has a significant effect on the brake noise; the brake pressure, friction coefficient and the brake drum’s young modulus have a great effect on the brake noise; the friction lining’s thickness and the brake shoe’s young modulus have a certain effect on the brake noise; the brake drum angular speed has little effect on the brake noise.