Portal frame of portal crane

The invention discloses a portal frame of a portal crane, which belongs to the technical field of cranes and comprises two bases, a plurality of moving wheels are arranged at the lower ends of the two bases, electric push rods are arranged in the middles of the lower ends of the bases, supporting frames are arranged at the output ends of the electric push rods, mounting frames are arranged at the upper ends of the two bases, and guide columns are arranged in the mounting frames. By arranging the lifting assembly, when the fixing plate needs to be adjusted at different heights, a motor is started to drive a first bevel gear to rotate, the first bevel gear rotates to drive a threaded column to rotate through a second bevel gear, the threaded column rotates to drive a guide column to ascend and descend through a threaded groove in the guide column, and therefore the effect of adjusting the fixing plate at different heights is achieved; the lifting assembly is arranged to adjust the height of the fixing plate mor