A modularized power supply switch control structure aims to control a main power system of a power supply. The main power system includes at least one high voltage output unit at a high voltage output end and one low voltage output unit at a rear low voltage output end. A control unit is connected to the high voltage output unit and the low voltage output unit to control start/stop time series of the high voltage output unit and the low voltage output unit so that the high voltage output unit and the low voltage output unit can be started asynchronously. Thus the power supply can output a start voltage at the start instant to meet load requirement. A plurality of power output modules deliver output asynchronously. Hence output current or voltage surge at the start instant can be improved.