Abstract: A humanoid robot joint was established. Two pieces of Mckibben muscles were used to actuate the joint. The force characteristic of Mckiben muscles was introduced simply. The relationship between Mckibben muscle length and the joint angle was calculated. The maximum of the joint angle was discussed in view of force analysis. The influence of connective position and structure parameters on the maximum of the joint angle was analyzed. The comparison between the artificial joint and human's was conducted. The result shows that both the contraction ratio of Mckibben muscles and the structure parameters of the joint have great influence on the joint angle. The appropriate connection position with the inboard Mckibben muscle can make the joint angle get its maximum.