A fuzzy balancing control method is proposed and implemented on a small-size humanoid robot named TWNHR-IV in this paper. The robot TWNHR-IV is able to stand and balance on an inclined plane by the proposed method. A 3-axis accelerometer is mounted on the robot TWNHR-IV, which has 26 degrees-of-freedom (DOFs), for obtaining the 3-axis accelerations of TWNHR-IV. The proposed fuzzy method includes two two-input-and-one-output fuzzy systems, the forward-and-backward fuzzy system and the right-and-left fuzzy system. Based on the obtained information from the 3-axis accelerometer, the proposed method is able to modify the feet posture to balance TWNHR-IV. Some practical experiments with different inclining situations are presented to illustrate the efficiency of the proposed fuzzy balancing control method.