The invention discloses a light emitting diode (LED) driving power supply and dimming system. The LED driving power supply and dimming system comprises an alternating current input rectifying filtering unit, a flyback conversion unit, an output filtering unit, a constant current output unit, a voltage feedback sampling unit, an optical coupling isolation unit, an STC 89C51 single chip microcomputer control module, a liquid crystal display module, a DS18B20 temperature measuring module, a buzzer warning module, an infrared sending module, an infrared receiving module and an auxiliary power supply module of a single chip microcomputer. The LED driving power supply and dimming system has the advantages of being high in efficiency, low in costs, convenient to control, simple in peripheral circuit and high in practicability.