A lamp device is controllable by a control terminal, and includes a light-emitting module, a driving circuit for driving the light-emitting module, a control unit for controlling duty cycle of the driving circuit, a first connector electrically coupled to the control unit, and a communication module. The communication module includes a second connector pluggably coupled to the first connector. The communication module is adapted to receive a control command from the control terminal and transmits the control command to the control unit via the first and second connectors, such that the control unit controls the driving circuit in accordance with the control command.