This study aimed to determine the population-based typologies of posttraumatic stress disorder (PTSD) symptomatology, the longitudinal patterns of transitions across these typologies, and the predictive effects of distress and fear disorder symptoms on these transitions in a frequently referred but scantly studied population of traumatized youth. A sample of 1,278 Chinese adolescents (54.0% girls) with a mean age of 13.4years (SD=0.8, range = 12-16) completed 2-wave surveys 2.5 and 3.5years after a major disaster. Psychopathological symptoms were assessed with the UCLA PTSD Reaction Index for DSM-IV, the Depression Self-Rating Scale for Children, and the Screen for Child Anxiety Related Emotional Disorders. Latent class analyses identified 4 classes characterized by high, reexperiencing/hypervigilance, dysphoria, and low symptoms, respectively at each time point. Latent transition analyses revealed relatively high levels of temporal stability within low symptom and dysphoria classes but relatively high probabilities of migration from re-experiencing/hypervigilance and high symptom classes into lower symptom classes. Multinomial logistic regression analyses found that some of the between-class movements during the year were predicted by baseline distress or fear disorders. This study provides an initial depiction of both quantitative and qualitative changes in youth's long-term PTSD symptom patterns over time and gives a further elucidation of other forms of posttrauma psychopathology's impacts on PTSD course. These findings carry implications for ongoing evaluation and adjustable intervention individually tailored to youth's PTSD manifestations and comorbidities in the long-term disaster aftermath.