Objective To explore the mediating effect of social support between the self-efficiency and the abstaining motivation in the drug addicts. Methods The two hundreds drug addicts were evaluated using the Social Support Rating Scale (SSRS),the General Self-efficacy Scale (GSES) and the Motivation Questionnaire of Abstaning from Drugs (MQAD), the mediating effect of social support was tested with multivariate stepwise regression analysis. Results The total scores of the SSRS,GSES and MQAD was (35.68 ± 5.81), (26.48 ± 4.84), (129.35 ± 11.49) respectively. The result of the bivariate correlation analysis showed that there were positive correlation among the social support, the self-efficiency and the motivation for abstaining from drugs(P<0.01). The values of the mediating effect of the social support was 0.2010, and its ratios to the total effect was 0.486 7, the ratio of the direct effect to the total effect was 0.513 3. Conclusions The Social support had significantly mediating role between the self-efficiency and motivation for abstaining from drugs in drug addicts. Improvement of the social support in drug addicts can promote their motivation for abstaining from drugs and abstaining confidence so that, it could make drug addicts to keep away from narcotics.