Adjustable diagonal strut for mounting prefabricated part of prefabricated building and using method of adjustable diagonal strut

The invention discloses an adjustable diagonal strut for mounting a prefabricated part of a prefabricated building and a using method of the adjustable diagonal strut. The strut comprises an adjustable rod and two connection parts which are fixed to a structure main body and the prefabricated part, wherein each connection part comprises a circular ring and an anchor plate fixed to the structure main body or the prefabricated part; the adjustable rod comprises a threaded casting, two screw rods which are partially screwed onto the two ends of the threaded casing, a hook fixing nut arranged on each screw rod, and a casing fixing nut arranged on each screw rod; a hook is arranged at one end, far away from the threaded casing, of each screw rod; the hooks can be hooked in the circular rings. According to the strut, the adjustable rod can be quickly and detachably connected with the structure main body and the prefabricated part in a manner of hooking the circular rings by the hooks; the adjustable rod has the function of supporting and fixing the prefabricated part and is capable of adjusting the verticality of the prefabricated part by adjusting the relative position between the threaded casing and the two screw rods.