The invention discloses a disassembling maintenance tool for a hydraulic mechanism pressure storage cylinder and a use method of the disassembling maintenance tool. The disassembling maintenance tool is suitable for the disassembling maintenance of a CY3 hydraulic mechanism pressure storage cylinder configured by a SW6-110kV circuit breaker. The tool includes a clamp used for clamping the pressure storage cylinder, a support, a screw rod, a screw rod sleeve fixed on the right side of the support, a front bearing and a rear bearing, wherein the front bearing and the rear bearing are arranged on the left side of the support; the clamp includes a front clamping block and a rear clamping block which are connected through a bolt and used for clamping the outer wall of the pressure storage cylinder, and the outer end of the front clamping block and the outer end of the rear clamping block are fixed with a front shaft and a rear shaft respectively; the front shaft and the rear shaft are located on the front bearing and the rear bearing respectively, the screw rod is screwed in the screw rod sleeve, and the head portion of the screw rod is provided with a thread head used for being connected with a pressure storage cylinder piston screw thread. The damage of high pressure release to the human body is prevented, the use method of the maintenance tool standardizes the operation behavior of maintenance personnel, and the safety of the maintenance personnel is ensured.