The invention is an automatic monitoring device for navaid light state. It includes dimmer powering primary loop, primary loop monitor and light position monitor in each light pit, the primary loop monitor is arranged with a receiving circuit, the light position monitor is arranged with a ejecting circuit. Its character lies in: there has a emitting circuit in the primary monitor, which includes isolating transformer B0, chopped wave signal ejecting circuit, dimmer reset circuit, chopped wave gating circuit, pulse isolating circuit, control instruction counting and coding N circuit, power industry frequency synchronous CP circuit and control switch K; the light position monitor is arranged with a receiving circuit, which including isolation transformer BMN, special transformer BZ, currentmutual inductor Hn, light position monitor power, follow-up peak sampling circuit, function switch circuit, delay circuit, it realizes the double-direction transmission and control of light position and light station with a long distance.