A kind of unidirectional bending joint was developed by using elongated artificial muscle. The relationship between the joint bending angle and the air pressure was analyzed by combining theory with experiment. When the air pressure is 0.4 MPa, the maximum clamping force of dual drive unidirectional bending joint is 21.11 n, and that of single drive unidirectional bending joint is 12.38 n; when the air pressure is 0.25 MPa, the bending angle of dual drive unidirectional bending joint is 235.4 ° and that of single drive unidirectional bending joint can reach 239.1 ° when air pressure is 0.35Mpa.