A power switch drive circuit with a built-in power supply capacitor, when the power switch (M1) reaches the turn-on threshold, it is discharged through the power supply capacitor (Cvcc) to turn on the power switch (M1), thereby saving the charge requirement on the power supply capacitor (Cvcc), and enabling a small-capacity power supply capacitor (Cvcc) to realize power switch (M1) driving. At the same time, the power supply capacitor (Cvcc) can be designed in an integrated circuit to improve reliability and reduce costs, therefore, it can solve the problem that the capacity of the power supply capacitor is too large to be able to be designed on the integrated circuit, which results in a large occupied space and an increased cost.