The invention discloses a temporary support device for a prefabricated air conditioner board, and belongs to the field of auxiliary tools for the erection of air conditioner boards. The aim is to provide the temporary supporting device for the prefabricated air-conditioning board, wherein the temporary supporting device is low in operational difficulty and high in installation precision and safetyfactor. The temporary supporting device is technically characterized by comprising the prefabricated air conditioner board, a hinging base, a prefabricated wall board and a fixing base and further comprising a fixing sleeve and a telescopic sleeve, one end of the telescopic sleeve is located inside the fixing sleeve, the other end of the telescopic sleeve is hinged to the hinging base, and the end, away from the telescopic sleeve, of the fixing sleeve is fixedly connected with the fixing base; an adjusting mechanism is arranged on the fixing sleeve and used for controlling the length of the part, extending out from the fixing sleeve, of the telescopic sleeve, a supporting rod is further vertically arranged on the part, close to the prefabricated wall board, of the fixing sleeve, a liftingrod capable of ascending and descending is arranged in the supporting rod, and the end, away from the supporting rod, of the lifting rod abuts against the prefabricated air conditioner board. The temporary supporting device is suitable for outdoor installation of the prefabricated air conditioner board.