The objective of this research was to study the effective of Group counseling based on rational emotive behavior theory with group dynamic to develop emotional quotient of substance use inmates. The sample were 24 substance use inmates in KhonKaen central prison. Who had low level of emotional quotient. They were randomly into the experimental group and control group, 12 inmates each group. The experimental group participated in group counseling based on rational emotive behavior theory with group dynamic to develop emotional quotient, 1 session a week, 90-120 minutes each session, total of 9 sessions. The control group did not participate in Group counseling, but they attended regular prison. The instrument using in this study were: The Emotional Quotient Assessment with reliability .86 and Discrimination 0.25-0.73 and The group counseling based on rational emotive behavior theory with group dynamic to develop emotional quotient of substance use inmates. Statistic using for data analysis was the Paired Simple T-test and Independent Simple T-test. The research finding found that the inmates participating in group counseling for developing the emotional quotient, obtained significantly higher score of emotional quotient than the pretest at .05 level. In addition, they had significant higher score than those who did not participate in group counseling at .05 level.