This paper proposes a new control method in Phase-Shifted Full-bridge converter for the server power supply, which is wide delay time of lagging-leg switches under the light load conditions. By widening the delay time, the switching is achieved at the lower drain-source voltage and switching loss can be reduced under the light load conditions. The voltage stress of synchronous rectifier switches is also reduced. Without additional power devices and side-effects at heavy load condition, the higher efficiency under the light load conditions can be obtained. The analysis and experimental results are presented in the paper to confirm the validity of this study.