The invention relates to a three-rotational-freedom parallel mechanism driven by a rope, which comprises a static platform, a dynamic platform, three driving branch chains and a fixed-length branch chain. Each driving branch chain consists of a lower revolute pair, a lower hooke joint, a rope hook, a motor, a rotating wheel, the rope, a pulley, an upper hooke joint and an upper revolute pair. The fixed-length branch chain consists of a hooke joint, a revolute pair and a supporting rod. The hooke joint is connected with the dynamic platform. The revolute pair is connected with the hooke joint. A rotating shaft of the revolute pair is connected with one end of the supporting rod. The other end of the supporting rod is fixedly combined with the static platform. The three-rotational-freedom parallel mechanism has the characteristics of large working space, simple structure, low manufacturing cost and easy installation. The fixed-length branch chain fixedly combined with the static platform plays a supporting role so as to provide enough rigidity for the mechanism. The three-rotational-freedom parallel mechanism can be applied to a large-scale attitude regulating and tracking device.