This study investigated psychiatric symptoms (depression, anxiety HP, and traumatic stress) during state-enforced quarantine among university students in China. We conducted a cross-sectional survey with 1,912 university students during March and April 2020. Psychiatric symptoms in the mild or higher range based on clinical cut-offs were alarmingly prevalent: 67.05% reported traumatic stress symptoms, 46.55% had depressive symptoms, and 34.73% reported anxiety HP symptoms. Further, 19.56% endorsed some degree of suicidal ideation HP. We explored factors that may contribute to poor psychological health as well as those that may function as protective factors. Risk and protective factors examined included demographic variables, two known protective factors for mental health (mindfulness, perceived social support), four COVID-specific factors (COVID-19 related efficacy, perceived COVID-19 threat, perceived COVID-19 societal stigma, COVID-19 prosocial behavior) and screen media usage. Across psychiatric symptom domains, mindfulness was associated with lower symptom severity, while COVID-19 related financial stress, perceived COVID-19 societal stigma, and perceived COVID-19 threat were associated with higher symptom severity. COVID-19 threat and COVID-19 stigma showed main and interactive effects in predicting all mental health outcomes, with their combination associated with highest symptom severity. Average screen media device usage was 6 hours and usage was positively associated with depression. Female TRANS gender TRANS and COVID-19 prosocial behavior were associated with higher anxiety HP, while COVID-19 self-efficacy associated with lower anxiety HP symptoms. Study limitations and implications for treatment and prevention of affective disorders during crisis are discussed.