The invention is suitable for the field of power switch tube driving, and particularly relates to an isolation drive circuit for a primary side power switch tube and a secondary side power switch tube of a to-be-isolated a switching power supply. The isolation drive circuit comprises a first capacitor, a second capacitor, a diode, a power switch tube and a resistor, wherein a negative electrode of the first capacitor is led out as an input end of the isolation drive circuit and is used for being connected with an output end of a primary side control chip; a cathode of the diode is connected with a positive electrode of the first capacitor; an anode of the diode is connected with the positive electrode of the second capacitor; a gate of the power switch tube is connected to the cathode of the diode through the resistor; and a source of the power switch tube is connected to the positive electrode of the second capacitor. A traditional isolation transformer is replaced with the capacitors, so that the structure of the drive circuit is simplified, the volume of the drive circuit is reduced, the cost is reduced, multi-branch parallel connection can be achieved by the drive circuit, a driver is provided for a converter module in parallel and effective isolation of switching power supply driving is achieved.