The accuracy of the disease diagnosis and the users'satisfaction with our expert system, it is caused by; (1) The model of knowledge representation for inference used the efficient factors which resulted in accurate disease diagnosis. The used factors were gender, age range, symptom, symptom significant weight and certainty factor of symptom occurred. (2) The system method used to obtain all symptoms completely which resulted in accurate disease diagnosis. Such as providing the symptom description and images caused the users specified the certainty factor of symptom accurately and questioning additional symptoms of possible disease. (3) Our mobile application has high efficiency and the application usage is easy and convenient.