This study examined the relationship between posttraumatic stress disorder (PTSD) and depressive symptoms among children who survived the Lushan earthquake. Three hundred thirty-three children (154 males, 179 females) were assessed for acute stress disorder (ASD) and depressive symptoms at 2 weeks (T1), and their PTSD and depressive symptoms were recorded at 1.5 (T2), 6 (T3), 12 (T4) and 24 (T5) months after the earthquake. The results showed that ASD predicted PTSD and depressive symptoms from T1 to T2, and PTSD symptoms predicted depressive symptoms from T2 to T5, but not vice versa. Depressive symptoms predicted avoidance from T1 to T5; in turn, avoidance predicted depressive symptoms from T3 to T5. Hyperarousal and intrusive symptoms had an effect on depressive symptoms between T1 and T2, and depressive symptoms predicted hyperarousal and intrusion from T2 to T3; after 12 months they did not significantly predict each other. The results suggest that PTSD symptoms generally precede depressive symptoms, and that hyperarousal and intrusive symptoms are major symptoms of PTSD soon after trauma events, while avoidance symptoms are major symptoms of PTSD late after trauma events. The relationship between PTSD and depressive symptoms mostly fits the interactive model.