The invention provides an expression search engine which comprises a communication module and an expression index module, wherein the communication module is used for receiving expression labeling information containing expression pictures and corresponding labeling texts; and the expression index module is used for generating an expression index file according to the expression labeling information. Compared with the prior art, the invention has the advantages that the expression search engine and an expression management system are used for acquiring the labeling information of expressions and establishing an index, so that sets of relevant expressions can be quickly researched through the labeling information of the expressions while an expression research service is provided, and a research result list can be returned, thereby the quantity of recalled effective results and the researching accuracy are improved, and the qualities of returned expressions are improved; and in addition, the expression picture sets can be sequenced through relevant coefficients, thus a user can quickly find out interested pictures from the research result list, and thereby the using convenience of the user is improved, and the network flow is saved.