The invention discloses a construction method for detaching a suspension bridge spatial main cable catwalk. In the catwalk detaching process, a pushing cross beam is arranged in a midspan, and a catwalk load-bearing rope on the external side of a main cable is fixed to the pushing cross beam by using a trolley; in the process of detaching a catwalk plane net, the catwalk load-bearing rope is gradually pushed, and the catwalk load-bearing rope on the external side of the main cable is gradually opened to control the catwalk load-bearing rope on the external side of the main cable to be not in contact with a lifting rod; after the surface layer of the catwalk is detached, a temporary bracket is mounted on the pushing cross beam in the midspan, a steel rope is connected with the catwalk load-bearing rope by using tower top winch pulley blocks on both shores, and then, by using the tower top pulley blocks on both shores, the catwalk load-bearing rope on the external side of the lifting rodis lowered to a steel box girder bridge deck after being lifted to cross over the main cable and an overhauling passage in sequence, and finally, the catwalk steel rope is recovered to finish detaching. According to the construction method for detaching the suspension bridge spatial main cable catwalk, the problem that the catwalk load-bearing rope and accessory members are in friction with the lifting rod to damage the lifting rod and shorten the service life of the suspension bridge under situations of a deadweight state of the catwalk load-bearing rope and high wind in the detaching process of the suspension bridge spatial main cable catwalk is solved.