Isolated primary circuit regulator

The invention discloses an isolated primary circuit regulator, which is applicable to a primary side of a transformer of a power supply. The isolated primary circuit regulator outputs a switching signal and can switch the transformer by the switching signal to further achieve an effect of stabilizing an output current. The isolated primary circuit regulator comprises a discharging time detector, an oscillator, a pulse width regulator and a control circuit, wherein the discharging time detector can be used for detecting the discharging time of a switching current which is generated on a secondary side of the transformer; the oscillator can be used for generating an oscillation signal; the control circuit can be used for outputting an adjustment signal; the pulse width regulator can output the switching signal according to the oscillation signal which is output by the oscillator and the adjustment signal which is output by the control circuit; and an operating period and a frequency of the switching signal corr