The invention relates to a method for accessing a new energy storage system to an UPS. The method comprises the following steps that: step S1: a double-bladed knife switch is added between a new energy storage accumulator and a PCS, the power supply input end of the double-bladed knife switch is connected with the new energy storage accumulator, one power supply output end thereof is connected with the PCS, the other power supply output end thereof is connected with a direct-current cable, and the double-bladed knife switch is switched between the PCS and the direct-current cable; step S2: the direct-current cable is connected with the input end of DC/DC equipment; step S3: the output end of the DC/DC equipment is connected to the direct-current input end of an UPS host through a single-bladed knife switch, the single-bladed knife switch is used for controlling the on/off of a connection circuit for the DC/DC equipment and the UPS host, the alternating-current input end of the UPS host is supplied with power by a low-voltage alternating-current circuit, and the UPS host is used for supplying power for a load. Compared with the prior art, the method disclosed by the invention has the advantages of being low in cost, energy-saving and environment-friendly, and the like.