(1) Background: The devastating Ms 7.1 earthquake struck Yushu city, China, in 2010, leading to serious consequences and damage in the central Tibetan Plateau. This study aimed to assess school adaptation and post-traumatic stress disorder (PTSD) symptoms of adolescent survivors five years after the Yushu earthquake. (2) Methods: A large-scale, school-based mental health survey was conducted 5 years after the earthquake among Tibetan students in the city of Yushu using the Adolescent’s School Adaptation Scale (ASAS) and the PTSD Checklist. (3) Results: A total of 1976 questionnaires were collected. A total of 30.7% of Tibetan adolescents had poor school adaptation and 19.5% were estimated as having probable PTSD. Logistic regression showed that females (OR = 0.73, 95% CI: 0.60–0.89), senior students (OR = 0.48, 95% CI: 0.39–0.59), and those who participated in post-disaster reconstruction (OR = 0.68, 95% CI: 0.54–0.85) were less likely to have poor school adaptation, while a positive association was observed among those buried under a collapsed building (OR = 1.47, 95% CI: 1.04–2.09) and those who experienced bereavement (OR = 1.77, 95% CI: 1.27–2.45). Students who had experienced bereavement were also more likely to have PTSD (OR = 1.60, 95% CI: 1.12–2.28). (4) Conclusions: The post-traumatic effects of the Yushu earthquake on Tibetan adolescents were severe and long-lasting. Sustainable long-term mental health services to help adolescents to restructure their mental health are necessary.