Pin shaft disassembling and assembling tool and method for mounting and removing variable pitch oil cylinder on and from hub

The invention discloses a pin shaft disassembling and assembling tool and a method for mounting and removing a variable pitch oil cylinder on and from a hub. The pin shaft disassembling and assemblingtool is used for disassembling and assembling the variable pitch oil cylinder, and two ends of the variable pitch oil cylinder are respectively fixed on the hub through pin shafts and pin shaft supports. The pin shaft disassembling and assembling tool comprises a jack, and a pin shaft tool sleeve with one end connected with the jack and the other end connected with the pin shaft supports. A jacking head of the jack penetrates through the pin shaft tool sleeve and is connected with the pin shafts. The jacking head reciprocates in the axis direction of the pin shaft tool sleeve to drive the pinshafts to move close to or away from the pin shaft supports so as to mount or dismount the pin shafts. Mounting and dismounting of the pin shafts are achieved through the acting force of the jack, mounting and dismounting of