Greenhouse crop has many advantages: high yield, high profit, growth in whole year, big demand in market. Having a relatively close space, greenhouse is featured with high humidity and low illumination; also, plant diseases and insect pests invade greenhouse crop easily. Intelligent monitoring and control of crops-based ecosystem health in greenhouse is a new direction of information agriculture. This paper reported a case study to show the success that data from greenhouse can be used intelligently to make decision in management of tomato development and prevention of tomato diseases and pests. GH-Healthex system utilizes data in the fields of crop wardship and intelligent prevention of greenhouse crop diseases and pests. To achieve high yield, high quality and efficiency in tomato production, the computer-logged data from greenhouse by combination of managing knowledge in tomato growth, plant diseases and insect pests were analyzed. When climate harmful to tomato occurs, the system can prompt users to carry out reasonable managements. This system provides a knowledge platform and general database, so user can use it also for other crops, not only tomato.