A LED lighting system, based on the luminance signal sending module, the luminance signal receiving module, and the rightness adjustment module, has been designed to overcome the defects of current LED lighting dimming system, which fails to regulate the multi-grade stepless dimming. A bidirectional thyristor alternating current phase shift circuit has been adopted by this new system for an output in voltage waveform of a luminance signal with positive and negative half wave loss, which signal will be converted into luminance data based on double-digit ternary system. The converted luminance signal, then via a single live wire, will be sent to the the luminance signal receiving module, where it will be captured, identified and converted into a PWM signal with an adjustable duty ratio by a micro-controller. The PWM signal, sent out by the LED drive, is able to adjust the brightness of LED lighting lamps, thus realizing the multi-grade stepless dimming control within the range of 0~100%. The feasibility of the dimming system has thus been verified by experiments, with the desired results fully achieved.