The invention discloses a method and a device for identifying a semantic structure of network information. The semantic structure comprises a plurality of semantic comments of the network page information content related to the semantics, properties of the commented information, and relations among the semantic comments. The method comprises the following steps: storing into a semantic structure tree in the system by defining the semantic structure of a sample page; generating a semantic tree identification command and a semantic tree validity identification command; and storing a semantic structure description file, a semantic tree identification command file and a semantic tree validity identification file in an external storage after the semantic tree identification command and the semantic tree validity identification command are verified. The semantic structure of the network page information, which is defined and identified by the method and the device of the invention, can be used by various systems, such as an information extraction system, a full-text and semantic search system, a commercial information mining system, an information syndication system, a network knowledgebase system and the like.