The invention discloses a lamp dimming circuit, which comprises an AC/DC (Alternating Current/Direct Current) power circuit, a dimming circuit and an LED (Light-Emitting Diode) lamp set, wherein the input end of the AC/DC power circuit is connected with commercial power, and the output end of the AC/DC power circuit is connected with the input end of a transformer and the input end of the dimming circuit; the output end of the transformer is connected with the LED lamp set; the output end of the dimming circuit is connected with the input end of the transformer. According to the lamp dimming circuit, a live wire, a neutral line and a ground wire are adopted for dimming, so that the problem of incapability of a power carrier in dimming is completely solved, and the problem of high cost of a single clamp control technology for a BUS intelligent system is completely solved; moreover, the lamp dimming circuit can be manually controlled, so that high stability and safety is ensured; the lamp dimming circuit is widely applied to the field of electric illumination control circuits.