The utility model discloses a portable bolt dismouting hydraulic wrench, including the pneumatic cylinder that contains the hydraulic stem, the lower end connection of pneumatic cylinder strikes the spanner, the last end connection of pneumatic cylinder has the connecting rod, the lower tip of connecting rod with the middle part of strikeing the spanner is connected, the upper and lower both ends of pneumatic cylinder are provided with quick -operation joint respectively. The utility model discloses can effectively improve the maintenance efficiency of well control equipment such as preventer, production tree, reduce personnel intensity of labour, reduce the safe risk coefficient in the maintenance process to reduce maintenance manufacturing cost.