Objectives: To evaluate the effects of ear points pressing at ear meridian points on obesity-related parameters( body weight, body fat, body mass index, waist, hip circumferences, and WC/HC ratio) between treatment and control groups, and we also apply the Self-Determination Theory to discuss the relationship between motivation and performance of body weight control. Methods: The study was an cross over open-parallel randomized control trial and the sample consisted of 189 volunteers who were randomly divided into two groups and the baseline characteristics were similar. In the experimental (immediate treatment) group (n=93), ear points pressing at five ear meridian points and lifestyle education were applied, while volunteers in the control (delay treatment) group (n=96) just receive lifestyle education in the first 8 weeks. At baseline, 24th, 32nd and each week of the sixteen weeks study, the outcomes mentioned above were examined in all volunteers, and related SDT questionnaires were checked during the period of 32 weeks study. Results: The result showed a statistically significant drop in BW, BMI, Waist circumference and Hip circumference during the 32 weeks in experimental (immediate treatment) and control (delay treatment) group, and better effect while using ear points pressing in the same group. But, no significant differences were found between the two groups. A SEM analysis showed that autonomous support, relatedness and original autonomy can get better competence and was related to positive consequences in BW control. And it was relative an adequate model to test the self determination theory. Conclusion: Even though the result showed a statistically significant drop in BW, BMI, WC, HC during the 32 weeks treatment in experimental (immediate treatment) and control (delay treatment) groups, and better effect while using ear points pressing in the same group. But, no statistical significance change in BW related parameters were found between the two groups. Further studies are needed to detect the effect of ear points pressing and model fit of SDT application by increasing research time, and sample sizes.