The application discloses a power mechanism and a slave operating device. The power mechanism, for connecting to an operating arm, includes a body and a power mechanism. A side surface of the body defines a mounting groove. The mounting groove passes through a bottom surface of the body. A distal end of the operating arm is located out of the mounting groove. The power portion is disposed on the body for connecting to the operating arm and providing power for the operating arm. The above power mechanism enables the operating arm to be simpler and more rapid to install.