Abstract: A light device comprising a light emitting unit, a voltage control unit, and a current control unit is provided. The light emitting unit is capable of receiving DC power. The voltage control unit has a power input terminal, a power output terminal, and a voltage setting member, with the power input terminal connecting with the light emitting unit, the voltage setting member having a threshold value to control the voltage of the power output terminal in a value equal to or lower than the threshold value. The current control unit has a voltage regulating member and a current adjusting member, with the voltage regulating member connecting with the power output terminal of the voltage control unit and generating a stable DC voltage, and with the current adjusting member connected between the voltage regulating member and a ground point to stabilize a current passing through the current adjusting member.