The invention discloses an LED dimming control system, which is composed of an MCU unit, a current sampling circuit, a voltage sampling circuit, a temperature sampling circuit, a current loop circuit, a voltage loop circuit, a PWM sampling circuit and a single bus communication circuit, wherein the current sampling circuit, the voltage sampling circuit, the temperature sampling circuit, the current loop circuit, the voltage loop circuit and the PWM sampling circuit are respectively connected with the MCU unit; and the single bus communication circuit is connected with the PWM sampling circuit via a control bus. a single chip microcomputer is used for controlling an LED power supply, the MCU developed on the basis can have a strong control function and a real-time monitoring function, effects of controlling current outputted by the LED power supply and limiting the maximum load voltage are achieved, the five-in-one control bus also integrates AD 0-10V dimming serial communication and PWM duty ratio control, constant power and constant current dimming functions are realized, and the operation is simple and convenient.