Abstract: Cooperative service of agricultural information (CSAI) is now becoming an important aspect of agriculture informatization. More and more attention has been paid to CSAI in the domain of agriculture informatization. Ontological concept into agricultural production and operation process (APOP) were introduced in the paper. Based on a few concepts concerned with CSAI, the division of the production and operation phase of dairy industry were studied and established, the corresponding information unit was built, and the process ontology of dairy industry and the business chain model (BCM) was constructed. Based on BCM, the framework of the cooperative service system of dairy industry information was set up, and the service functions in a prototype system was then realized. The result shows that the agricultural process ontology (APO) on the biological characteristics has its own obvious advantages as a classification standard of agricultural information; the business chain model based on APO could effectively deal with the optimal operation and the cooperative service mechanism of agricultural information. The cooperative service of search engine and agricultural web-site was achieved.