The present invention provides a method for resource information backup operation based on peer to peer network, comprising: an initiating node sending an out-of-domain backup node determining request to a connecting node in backup domain, and said out-of-domain backup node determining request including the resource global identifier of said resource information to be backed up, and the connecting node in said backup domain and said host node in which the resource information is saved have different domain identifiers; the connecting node in said backup domain determining an out-of-domain backup node according to information of said resource global identifier and out-of-domain backup rules, and sending routing information of said out-of-domain backup node to said initiating node; and said initiating node sending an out-of-domain backup operation request to said out-of-domain backup node according to said routing information, and said out-of-domain backup node implementing corresponding processing according to said out-of-domain backup operation request.