The invention discloses a DL/ T860 model auxiliary system for a power supply of a transformer substation and a working method of the DL/ T860 model auxiliary system. The DL/ T860 model auxiliary system comprises an ICD (Interface Control Document) generating module, an online loading module and an ICD model document detecting module; the ICD generating module is used for customizing a forwarding table according to user requirement and generating an ICD model document according to the DL/ T860 standard; the online loading module is used for updating a lower computer online; the ICD model document detection module is used for detecting whether the ICD model document meets the DL/ T860 standard. The DL/ T860 model auxiliary system has the advantage that different IED model documents can be quickly generated through auxiliary software according to different phenomena in the site.