An electrode assembly manufacturing device includes a winding mechanism, a heating mechanism, a conveyor belt arranged between the heating mechanism and the winding mechanism, and a forming mechanism. The winding mechanism is configured to wind a positive electrode sheet, a separator, and a negative electrode sheet into an electrode assembly. The conveyor belt is configured to transfer the electrode assembly from the winding mechanism to the heating mechanism. The heating mechanism is configured to heat the electrode assembly. The forming mechanism is configured to press and form the electrode assembly.