Introduction: Empowering and enhancing the life quality for drug addicts are effective steps to lead and assist them to absolute quitting of drugs. Objective: The present study was performed to observe the intervening effects of cognitive-behavioral trainings to improve quality of life and reduce aggression among drug addicts. Method: This study was an intervening controlled trial conducted on 30 cases of drug addicts. The population was the addicted prisoners in the Central Prison of Tehran in 2013. In responding to the quality of life scale and Aggression Scale, 30 drug addicts who gained a score lower than the cut off score quality of life scale in (lower than 63) and in Aggression Scale (higher than 73) were chosen and divided into control and experimental groups of 15 persons randomly. Then, before intervention sessions, both groups responded to the World Health Organization Quality of life Questionnaire (1998) and Aggression Scale (1992). The experimental group was under cognitive-behavioral trainings for12 sessions (each session 75 minutes) and control group did not receive any intervention. In order to analyzing data, the SPSS 18 software, and Levine and multivariate covariance tests were used. Results: Results of Levine test also showed that experimental and control groups are comparable to each other. Accordingly, the results of covariance analysis showed that there are significant differences in quality of life scores and aggression between the experimental and control groups (P<0/01). Conclusion: The results of the present study showed that the cognitive-behavioral trainings improve the quality of life and level of aggression among drug addicts. The results also can be used in the empowering and improving of the life quality of the quitting drug addicts.