Four-degree-of-freedom parallel mechanism

The invention discloses a four-degree-of-freedom parallel mechanism. The four-degree-of-freedom parallel mechanism comprises a holder, a movable platform, and four branch chains of the same structure arranged between the holder and the movable platform; each branch chain comprises a driving arm, a connecting shaft, two parallel and equally long driven arms and four T-shaped shafts, wherein the driving arm is rotatably connected with the holder; one ends of the driven arms are connected with the driving arm through the two corresponding T-shaped shafts, while the other ends of the driven arms are connected with the connecting shaft through the two corresponding T-shaped shafts; the connecting shaft is rotatably connected with the movable platform. The movable platform of the parallel mechanism is of a single platform structure so that the weight of a moving part can be reduced, and high-speed and high-acceleration dynamic response characteristics can be realized.