A light emitting device includes at least one light emitting unit, a micro controller and a control module. The control module includes a storage unit configured to store a reference sheet between an intensity of the light emitting unit and a current value of the light emitting unit. A light emitting diode (LED) control unit is configured to receive a control signal from the micro controller. A digital-to-analogue conversion unit is configured to transform the current value and the on/off status to a simulation signal. A LED driver unit is configured to control the on/off status and the intensity of the light emitting unit based on the simulation signal. The control module further includes an input pin and an output pin, and the input pin is electrically connected with output pin in series when the multiple light emitting devices are provided.