Based on flexible pneumatic actuator (FPA), a new kind of flexible pneumatic side-sway joint was proposed. The side-sway joint is used for designing agricultural dexterous robot multi-fingered hand. The side-sway joint is basically composed of two FPAs. When the two FPAs were inflated with different compressed air pressure, the side-sway joint could realize left and right movement. The force equilibrium equation of the FPA free end was established. The static model of the side-sway joint was obtained, and the static model was also simplified. Experiments were carried out to verify the static model. Experimental results show that the experimental curve matched well with the simulated curve, and there was certain error between them (maximal static error is 0.035 rad). The error cause was analyzed. Then the experiments were carried out to measure the dynamic performances of the side-sway joint. Experimental results show that the step response time of the joint was about 2 s (steady value’s tolerance zone ?=5%) respected to different expected angle step signals. The side-sway joint can significantly increase the workspace and further improve the adaptability and dexterity of the agricultural dexterous robot hand.