Tower crane with safety protection function

The tower crane with the safety protection function comprises a slewing mechanism (900) composed of a lower support (10) and an upper support (20), a rotating shaft (22) is fixedly arranged in the middle of the bottom face of the upper support (20), the lower end of the rotating shaft (22) is rotationally connected with the interior of the lower support (10), and a spline groove (13) is formed in the position, located on the outer wall of the rotating shaft (22), of the top face of the lower support (10). The outer wall, located on the upper side of the spline groove (13), of the rotating shaft (22) is sequentially connected with an annular clamping block (221), an annular suction cup (222) and an annular friction sleeve (223) in a sleeved mode, the top face, corresponding to the annular friction sleeve (223), of the lower support (10) is provided with a brake assembly (30), and the brake assembly (30) comprises a mounting support (31), a second electromagnet (32), a sliding sleeve (33), a brake block (34) an