Abstract: This disclosure discloses a light-emitting device adapted for receiving an alternating current signal from a power source. The light-emitting device comprises: a rectifying unit for receiving and regulating the alternating current signal into a first direct current signal; a first capacitor electrically connected in parallel with the rectifying unit and for receiving and regulating the first direct current signal to a second direct current signal; and a light-emitting unit electrically connected in parallel with the first capacitor and receiving the second direct current signal. The second direct current signal is a periodic signal, and the second direct current signal has a maximum voltage and a minimum voltage. The voltage difference between the maximum and minimum voltages is less than 5% of the maximum voltage in one cycle of the periodic signal.