The utility model provides an oil logging instrument's shell dismounting device, includes hydraulic drive, clutch a device and a pad section of thick bamboo 3, wherein: hydraulic drive includes the pneumatic cylinder 1 of 5 constitutions of cylinder liner, plunger and control valve to and connect the power push rod 7 at 1 plunger output of pneumatic cylinder, connect the afterburning pole 8 at 1 plunger input of pneumatic cylinder, and at cylinder liner lower part extension threaded sleeve pipe 6, promptly the device includes that threaded connection cover 9, several clutch arm 10 and lock sleeve 4, fill up a section of thick bamboo and be 3 and be two-way U-shaped structure on, not the U-shaped mouth and peg graft with power push rod 7 and cooperate, establish screw thread 18 in the U-shaped mouth of lower part, be connected the cooperation with logging instrument's the connector thread of company, hydraulic drive pass through threaded bush 6 and the cooperation of threaded connection cover 9 threaded connection with device promptly, it constitutes the cooperation of pegging graft to fill up a section of thick bamboo 3 and clutch 10 lower extremes on the arm. Have: simple structure, convenient to use, low cost, can be under the circumstances of the inside device safety of guarantee oil logging instrument, dismantle the shell of instrument safely.