The invention discloses a rotary derrick cap which comprises a sleeve cap for being connected with a derrick body. A cylindrical column vertical to the sleeve cap is fixedly connected onto the upper end surface of the sleeve cap, and the peripheral wall of the column is provided with a hoisting component and an anchor frame successively from bottom to top which are assembled with the outer periphery of the column. The hoisting component comprises a frame-structure square support frame which is sleeved on the column through a cylinder and rotates around the column, and four corners of the square support frame are provided with pulleys for hoisting tower materials respectively. An anchor rod is arranged on a central axis of the square support frame, two ends of the anchor rod are provided with anchor holes respectively which are used for threading anchors controlling the rotation direction of the derrick cap, and hoisting holes for mounting the pulleys are further arranged on the anchor rod. The rotary derrick cap can rotate freely for 360 degrees, the technology of outside anchor and inside suspension is achieved, and simultaneously, tower materials of various weights can be hoisted, the engineering efficiency is improved, and the construction safety is guaranteed.