Abstract: In view of the problems of unstable walking and even falling down caused by the yaw moment around zero moment point (ZMP) when the humanoid robot walks, a method for counteracting the yaw moment based on arms swinging is proposed. The cause of the yaw moment and its effect on the robot walking stability are analyzed. According to the link model of humanoid robot and the single pendulum model of arm swinging, the expression of moment generated by arms swinging is deduced, and the principle of counteracting yaw moment with the arms swinging moment is formulated by using the illustration of arms swinging. With the adoption of cubic spline interpolation, the parametric angle trajectories of arms swinging are planned. Through the exhaustive search algorithm, the angle parameters are traversed to guarantee the yaw moment to be mostly counteracted by the arms swinging moment. The simulation result verifies that the method can not only counteract the yaw moment greatly to ensure walking stability of the humanoid robot, but also guarantee the monotonicity, the smoothness and the periodicity of the angle trajectories of arms swinging.