The invention discloses a digital switching power source with high light-load efficiency. The digital switching power source comprises an alternating current input power source, an EMI filter, a rectifier bridge, a pre PFC correcting circuit, a transformer, a post DC/DC conversion circuit, a sampling circuit, a first drive circuit, a second drive circuit, a first DSC and a second DSC. The light-load efficiency is improved by reducing the switching loss of a MOS pipe in the pre PFC correcting circuit, the switching loss of a MOS pipe in the post DC/DC conversion circuit and the magnetic core loss of an inductor on the condition of light loads. Compared with other methods for improving light-load efficiency, no additional circuit is needed, and the purpose of improving the high-load efficiency of the power source can be achieved only by using an original control circuit and simply changing relates control strategies; therefore, the digital switching power source is high in light-load efficiency, simple in structure, low in cost and good in reliability.