The invention provides a posture-adjustable multifunctional ROV torque wrench. The posture-adjustable multifunctional ROV torque wrench comprises a torque wrench interface, a locking device, a hydraulic driving mechanism, a torque switching mechanism, a guide base and a torque wrench control monitoring system. Torque is provided by a hydraulic motor, an appropriate torque gear is switched by the torque switching mechanism, and the torque is amplified by a torque amplifier and then transmitted to the torque wrench interface. The torque switching mechanism can switch the gear of the output torque, and the torque gear can be displayed by an indicating needle. The torque wrench interface can be in but connection with a rotary butt joint interface meeting the Class I-IV grade in SO 13628-8 interface standards, the locking device can lock the rotary butt joint interface, and connection stability in the rotating process is ensured. The guide base can be mounted on an ROV and finely adjusts the posture of the torque wrench. The torque wrench control monitoring system can control the torque wrench by controlling the actions of the hydraulic cylinder and the hydraulic motor, and feeds the operation state back to a control interface in real time. The posture-adjustable multifunctional ROV torque wrench is convenient and fast to operate, stable and reliable.