Exposure to traumatic events can be associated with a large number of negative psychological outcomes and behaviors, particularly substance abuse is the most typical behaviors. Studies indicated that substance abuse may impair adolescents’ academic performance in school, and even leads to self-injure behaviors. While studies found traumatic exposure has direct positive effect on substance abuse in traumatized people, we don't know exactly about the mechanisms or the role of other factors in the relationship between traumatic exposure and substance abuse. According to relevant theories, PTSD and attachment plays an important role. It has been documented that PTSD is a common and representative posttraumatic reaction, and it involves intrusive symptom, hyper-arousal symptom, and avoidance symptom. According to self-medication hypothesis, people with PTSD symptoms use nicotine or alcohol to alleviate subjective states of distress. Therefore, substance abuse is probably a coping style for those people to self-mediate the affective flooding or numbing involved in this condition. Additionally, world assumption hypothesis suggested that individuals’ assumptions about this world, themselves and others may be shattered by traumatic experiences, and then they may feel unsafe and unprotected, and hard to believe in others. This might further damage their parent attachment or peer attachment. Whereas insecure parent-child or peer attachment would lead to negative feelings and emotions, thus exacerbate the negative outcomes of traumatic events. Wherein, people can't feel warm or lack support from parents or peers, so they are more likely to use substance abuse. In addition, symptoms of PTSD may also further disrupt parent-child attachment or peer attachment. For these reasons, this study incorporates PTSD and attachment into exploration of relationships between traumatic exposure and substance abuse, examining the internal mechanism how traumatic exposure affect substance abuse. The current study used traumatic exposure questionnaire, posttraumatic stress disorder inventory, parent and peer attachment inventory and substance abuse questionnaire to investigates 1435 adolescents at 1.5 year after Wenchuan earthquake, and selects 354 adolescents who meet the criterion of substance abuse, 68.1% boys and 31.1% girls (Mage=15.17 years, SD=1.68 years). The structural equation model was used to examine the relationship, and results found that traumatic exposure has no significant effect on substance abuse by peer attachment, and by PTSD via peer attachment. However, traumatic exposure has a direct and positive effect on substance abuse, but this effect is not significant after mediators was entered. In addition, traumatic exposure has indirect and positive effect on substance abuse by PTSD and parent attachment, respectively. More importantly, traumatic exposure also has a multiple indirect effect on substance abuse by PTSD via parent attachment. In summary, the results indicated parent attachment plays more important role than peer attachment in such a significant cases as earthquake. It suggests that traumatic event itself doesn’t destroy adolescents’ parent attachment, instead may enhance their attachment to parents. In this condition, support or company from their parents may decrease substance behavior. But when they develop some PTSD symptoms, their parent attachment might be impaired under sense of powerlessness and out of control. Therefore they need a way to relieve their suffering, so substance abuse behaviors may increase. This study enriches the mechanisms between traumatic exposure and substance abuse among adolescents, which helps us to better understand their behaviors after earthquake. This results remind us to consider specific negative symptoms of each individuals after traumatic events, and focus on their parent attachment, exploring more about how they feel about themselves and their parents after earthquake. So we can take corresponding measures to intervene with these guidance, and help them recover from the disaster.