Abstract: Due to the difficulty to access the web-based fish disease diagnosis system for users in rural areas, a fish disease diagnosis platform was developed based on the wide coverage of mobile signal and the convenient use of short message service (SMS) in order to solve fish disease problems in countryside. By the analysis of its function, user-input code and diagnosis process were designed in the platform, and the system function was developed in Java. The system can provide service for users to inquire fish disease diagnosis through short message. As the result certified, the platform can reply to users in 20 seconds on average with a high accurate rate of 93.57% for diagnoses of fresh-water-fish diseases in Tianjin area in China. It can prompt the application of intelligent-diagnosis technology for fish disease and expand the coverage of fish disease diagnosis knowledge in rural areas in China.