Direct-current power supply with power failure retention time

The invention provides a direct-current power supply with power failure retention time, which comprises a busbar voltage backfill preventing circuit and a capacitor switch circuit, wherein the input end of the capacitor switch circuit is connected with the output end of the busbar voltage backfill preventing circuit, a capacitor boosting circuit is connected to the capacitor switch circuit, and the output end of the capacitor switch circuit is connected with the input end of an output discharge circuit. According to the invention, the power failure retention time controllability of the product is realized, and the power consumption and the cost of the power supply of a base station are greatly saved.