The invention discloses a distributed maintenance-free intelligent direct current power supply system based on single batteries and a control method thereof. The system comprises at least one group of storage batteries and a distributed maintenance module connected with the storage batteries, the distributed maintenance module is connected with an intelligent control system, and the intelligent control system is connected with the storage batteries through an online bridge connection module and a UPS direct current system. According to the system, the newest power electronic technology and the embedded technology are employed, and a distributed intelligent charging, discharging, and monitoring integrated module is developed; determination of failed batteries, online bridge connection of failure batteries, and online capacity checking are realized; the conventional mode of a direct current cabinet, battery tour inspection, and manual regular maintenance is replaced by the extensible distributed module and a unified background; the conventional mode of regular checking of the capacity of the storage battery and discharging and charging maintenance is changed, and a technical realization method of the intelligent direct current power supply system for distributed online monitoring, online balanced maintenance, online activation, online capacity checking, online bridging of the failure batteries, and data remote transmission monitoring of the single batteries is provided.