Abstract:Disease and insect pests are the main limiting factors for crops to increase yield. In order to make the control decision more accurate and more scientific, a real-time monitoring and forecasting system based on internet was established for main crops diseases and insect pests of China, according to knowledge of the plant protection, expert experience, and utilizing artificial intelligence, geography information system (Gsystem1) which was developed by authors and decision support system (DSS) technology. The system could provide the real-time information on occurrence of more than 60 different kinds of diseases and pests in wheat, corn, rice, potato, sorghum and millet of China as well as diagnosing, knowledge providing and short-term controlling decision for nine kinds of important diseases and insect pests, including powdery mildew, sharp eyespot and scab of wheat, rice blast, rice false smut, potato late blight, aphids, grain gall midge of wheat and corn borer, based on crop resistance, primary level of pests and short-term weather forecast. It also had the function of comparing the status of each disease or insect pest during the same period in different years. It can transform data information into a geographical information map, to show the distribution and severity of diseases and pests. The running of the system could help people to control the harmful organisms in a more scientific way.