The invention provides a voltage regulation circuit of illuminating lights, which is suitable for an illumination system which is serially composed of a main power source and an illumination load. The single-phase illumination system comprises the main power source which outputs sine alternating current voltage, and the illumination load. The voltage regulation circuit of illuminating lights is in series connection in a loop which is formed by the main power source and the illumination load, and comprises a voltage regulation circuit and an auxiliary power source. The voltage regulation circuit is used for generating auxiliary voltage to regulate amplitude of the sine alternating current voltage which is loaded on the illumination load. Power consumption of the voltage regulation circuit of illuminating lights is small, harmonic wave loaded on the illumination load is also small, so that the alternating current voltage loaded on the illumination load is still of sine curve. The normal voltage requirement loaded by the illumination system is satisfied, in particular when being inputted with sine curved voltage, twinkling of an HID lamp or a fluorescent lamp is reduced, the power factor is enhanced, and the service life of an illuminating lamp is extended. In addition, the method is also suitable for other illuminating lamps inputted with the sine curved voltage.