Background and Purpose: The aim of this study was to investigate the effects of an 8-week Diet Education Program, which included diet education and behavior modification intervention of dietary cognition eating behavior and bodyweight of obese psychotic patients during their recovery. Methods: The design of the study was quasi-experimental using a purposive sampling in a regional teaching hospital recovery ward. The patients who fit the criteria of the study subjects were randomly assigned into the experiment group or control group. Each group had 26 participants. The Diet Education Program intervention in the experimental group included diet education and behavior modification. However, no interventions were taken in the control group. Collected data were analyzed using descriptive statistics, independent t-test, and ANCOVA. The significant level was α=.05. No statistically significant differences were shown among demographics or disease characteristics between the experimental group and control group. Results: The results indicated that after the 8-week Diet Education Program intervention, the experiment group showed significant difference between pre-and post experiment (p<.05). Conclusion: This study showed that the 8-week Diet Education Program intervention improved the obese psychotic patients' eating behavior, dietary cognition and loss bodyweight during recovery.