Internal step-down circuit structure of LED driving power source

The invention discloses an internal step-down circuit structure of an LED driving power source. According to the internal step-down circuit structure, a rectifier bridge circuit (1) is connected with a high voltage pre-step-down circuit (2); the high voltage pre-step-down circuit (2) is connected with a linear voltage stabilization circuit (5), a hysteresis detection circuit (3) and a pre-posed reference voltage circuit (4); the hysteresis detection circuit (3) detects and compares the voltage of the high voltage pre-step-down circuit (2) so as to control the on-off of the high voltage pre-step-down circuit (2); the pre-posed reference voltage circuit (4) outputs a reference voltage which does not fluctuate with an input power source, does not change with temperature and is adopted as the reference voltage of the hysteresis detection circuit (3) and the linear voltage stabilization circuit (5); and the linear voltage stabilization circuit (5) performs voltage stabilization on the output voltage of the high vo