The present invention relates to the field of medical appliances, more particularly to a communication system of an implantable device, comprising an external unit and an implantable unit, wherein the external unit and the implantable unit realize charging and bidirectional signal transmission of the external unit to the implantable unit by a wireless signal, two coupling coils are disposed outside the body, one for transmitting the forward signal, and one for receiving the reverse signal, and one coupling coil is disposed in the body for receiving and feeding back the signal, wherein the setting of the shape and position of the two coupling coils outside the body avoids the reverse signal fed back from inside of the body to be disturbed, thereby achieving effective transmission of the bidirectional signal, and overcoming the problem that the signal has weak signal strength and tends to be interfered when the traditional implantable device transmits the signal in a reverse direction.
