This study aimed to understand middle-aged and elderly people’s behaviors to prevent and control chronic diseases, and to discuss the association between major chronic diseases, self-awareness of health, BMI and health behaviors. Research data were taken from the database of the 2007 Survey on Middle-Aged and Elderly People’s Physical, Psychological and Social Life Conditions conducted by the Bureau of Health Promotion. A total of 4,112 subjects who answered questionnaires by themselves were selected. The SPSS 12 was used to analyze and describe middle-aged and elderly people’s behaviors to prevent and control chronic diseases. Data were then subject to Chi-square tests, Pearson correlation analysis and first-stage partial correlation analysis to analyze the association between preventive behaviors of chronic diseases and other variables. As indicated by research results, among behaviors to prevent chronic diseases, weight control, and less frequent smoking or quitting smoking occupied 33.6% and 27.7% respectively; less frequent drinking alcohol or quitting drinking alcohol accounted for 41.4%; having an exercise habit, diet control and regular lifestyle occupied 61.0%, 64.7% and 67.5% respectively. According to most of the middle-aged and elderly people, they controlled their diet to prevent and control chronic diseases. Their second choice was to control body weight. BMI and weight control were found significantly associated with prevention and control of chronic diseases, indicating middle-aged and elderly people are in need of information about diet control and weight control. The analytical results targeting middle-aged and elderly people with different background could be provided as references to relevant institutions when giving health education to different groups of people.