The basic medical insurance is an important part of social security system. Although Xiamen has done a greater job in medical security than the other cities in Fujian Province, it still needs measures taken to improve the system. This paper starts with a brief introduction of medical insurance in Xiamen, then deeper analyzes the demanding group of people by methods of factor analysis and decision tree analysis, and ultimately compares the medical system of city and countryside. The results show that there is much less proportion of insurants in commercial medical insurance than the basic, current medical insurance doesn't sufficiently cover the cost of major disease, and urban residents have higher satisfaction in medical insurance than rural households. Regarding these findings, the paper brings up suggestions concerning strengthening the commercial medical insurance, establishing insurance programs for special circumstances, and setting up city-country integrate system of medical insurance.