The scheme and practice for construct of intelligent agricultural information network are descibed . With Internet form, we set up the computer network of Intelligent Information Technology of Agriculture in Demonstration Section of Chongqing, discussed the design method of expert system in agriculture, and studied 5 expert systems based on vegetable growth, such as tomato and so on. Some software modules are studied, such as the soil information systems on the network, expert system in the vegetable plant diseases and insect pests diagnostician and network on line selling and so on. The structure,function and work flow of information service system based network are introduced.