The invention provides a method of integrating a server using alternating current power (AC server) into a server system using direct current power (DC server system) and an alternative junction device therefor. The integrating method includes: providing an AC server having a plug-in power supply unit; providing an alternative junction device for replacing the plug-in power supply unit; extracting the plug-in power supply unit from the AC server; plugging the alternative junction device into the AC server; and coupling the alternative junction device to a direct current power supply unit of a DC server system. The alternative junction device includes: a shell to be installed into a containing slot of an AC server; an output coupled to a DC input of a processor of the AC server when the shell is installed into the containing slot; and an input coupled to a DC power supply unit of a DC server system.