An electric actuator includes: an actuating shaft and a screw rod screwed to and driving the actuating shaft a motor connecting the screw rod a connection seat connecting the actuating shaft and including a positioning post and a rotary shaft a coupling ring sleeved around and rotating with the positing post, and a slide slot disposed out of the coupling ring a support ring sleeved around the rotary shaft a cylindrical connector sleeved around the support ring and screwed to a hinge end cap and with a locking slot communicating with the slide slot and disposed out of the cylindrical connector a knob sleeved around the cylindrical connector and the coupling ring and covering the rotary shaft, and a raised rib slidably connected to the slide slot and the locking slot and disposed in the knob.
