Abstract: To provide cheap, convenient and effective general peasants services of agricultural intelligent diagnosis system, a new design approach of intelligent system was proposed in this paper based on Android mobile terminal for diagnosing the agricultural pest insects and disease. A universal database and programming environment which was easy to do secondary development and rich in human-computer interaction technologies was constructed. Production-rules and forward reasoning method were applied to figure out the tree diagrams and inference engine for sweet corn pest insects and diseases. The research of system developing was focused on based on Android mobile terminal to realize the intelligent diagnosing on sweet corn pest insects and diseases. The developing approach of this new system was general-purposed. The test and application results of this system showed that this system was benefit for the agricultural production in practice with excellent features as portable, friendly interface and unlimited with networks.