The invention discloses an end effector used for demounting a nut of a high-tension transmission line and a robot and relates to the field of robots. The end effector comprises an executing module, a driving module and a joint part. The executing module comprises a worm wheel shaft, a worm wheel is firmly and fixedly connected to the worm wheel shaft, and a universal sleeve is firmly and fixedly connected with the tail end of the worm wheel shaft. The worm wheel is meshed with a worm, the universal sleeve is driven to rotate, and therefore the nut on the high-tension transmission line is demounted. The driving module is connected with the worm and used for driving the worm to move. The head end of the joint part is connected with the executing module, and the tail end of the joint part is used for being connected with an operation arm of the robot. The end effector is compact in structure and can adapt to nuts of various specifications, and therefore butt joint of the operation arm of the robot is facilitated.