The invention discloses a water-cooling electric outboard engine, comprising an engine body and a support. A control assembly including a motor and a control handle is arranged at the upper part of the engine body; a motor connector is arranged inside the engine body; the control assembly also comprises a controller; a motor water jacket and a controller water jacket are respectively arranged on the motor and the controller; the motor connector is connected with the motor water jacket by a first water pipe; the motor water jacket is connected with the controller water jacket by a second waterpipe; the controller water jacket is connected with the motor connector by a third water pipe; the motor connector is communicated with the water inlet and backwater port at the bottom of the engine body by an inlet pipe and an outlet pipe; a pump is arranged at the lower part of a driving shaft. The water-cooling electric outboard engine utilizes the pump driven by the driving shaft to transportthe cooling water into the motor water jacket and the controller water jacket as well as form a cooling water circulating system, thus exerting water cooling effects to the motor and the controller.