A lamp includes a lighting module providing illumination, a control unit, and a detecting unit. The control unit is connected or not connected to the lighting module. The detecting unit is coupled to the control unit. The detecting unit detects operational statuses of the lighting module and sends a detection result to the control unit. The control unit controls the lighting module or an alarm unit to enter an alarm mode based on the detection result. A user can immediately know the operational statuses by the alarm unit and take necessary actions to assure normal operation of the lamp.