The aim of the study was to evaluate the effectiveness of interventions based on positive psychotherapy on improving coping styles, relapse prevention in individuals diagnosed with substance use disorder. The research design was quasi-experimental with pretest-posttest, a month Follow-up and control group. Thirty-one individuals with substance use disorder, who were admitted to addiction treatment centers in Zahedan city, were selected through purposeful sampling method and were randomly assigned to an experimental (14 persons) and control (17 persons) groups. Both groups were asked to respond to Coping Styles Questionnaire by Billings and Mouse, at the pretest stage. In later stages of research, the experimental group received an intervention based on positive psychotherapy for ten sessions each session60 minutes. Data was analyzed using covariance and chi-square test. The results showed that intervention based on positive psychotherapy improved the coping styles and relapse prevention in the experimental group and the effect of the intervention was significant in post-test and follow-up stages. The result also showed that interventions based on positive psychotherapy could be used as an efficient technique to improve coping skills and relapse prevention in patients with substance use disorder.