The utility model discloses a resistance, voltage and PWM three-in-one LED intelligent dimming circuit. The LED intelligent dimming circuit comprises a single chip microcomputer microprocessor unit power supply circuit, a microampere-level constant current circuit used for converting external dimming resistance signals into voltage signals, a D/A digital analog conversion circuit composed of a three-order low-pass filter, and a single chip microcomputer (MCU) interface circuit. The resistance, voltage and PWM three-in-one LED intelligent dimming circuit of the utility model is compatible with three dimming modes mainly adopted in the prior art, and finally, resistance, voltage and PWM signals are inputted to two signal input lines in an unified manner, and therefore, different dimming requirements can be satisfied; current that a user needs to control and output is guided according to a relation diagram between dimming signals and output current. The resistance, voltage and PWM three-in-one LED intelligent dimming circuit has greater flexibility. Since the single chip microcomputer (MCU) is adopted, a relation between dimming signals and current outputted by a driver can be conveniently modified.