The switched power supply based on timing control has been widely used in the millimeter wave system. The principle of timing control was analyzed. Various factors influencing the performances of timing control were taken into consideration. The existing schemes of timing control were analyzed. A kind of basic method of timing control for switched power supply was proposed. Based on the methods, a more comprehensive study was made to estimate effects of timing control, including power on, power off, short-circuit or over-current protection. And a topology suit to timing control was proposed. Finally, a demo board was designed based on the topology. Both simulation and test results showed that the circuit met design specifications.