The paper introduces the design and development background of mobile terminal application "medical assistant" platform, as well as its principles, namely, practicability, safety and openness. It concretely introduces the design plan of 3-layer system architecture, network and storage security design status, through installing "medical assistant" application client in the patients' mobile telephone, the functions including medical information query, browsing, consulting, making appointment, registration, payment are realized, so as to satisfy the information demands of patients in different levels.