Background: Revealing the dynamic interplay between posttraumatic stress disorder (PTSD) symptom clusters has always been an important topic in traumatic stress studies. Based on longitudinal studies, different hypotheses have been proposed to explain PTSD symptom dynamics. But currently, no study have been conducted to test these hypotheses in children and adolescents. Methods: Data were derived from a longitudinal study of child and adolescent traumatic event survivors of an explosion accident (N = 659). DSM-5 PTSD symptoms was measured by the PTSD Checklist-5 (PCL-5) at 4, 8, and 13 months after the disaster. Latent difference score (LDS) modeling was used to evaluate the dynamic interplay between clusters. Results: The results of LDS model indicated that intrusion level positively predicted subsequent rate of increase for hyperarousal (p =.008) and negative changes in cognitions and mood symptoms (p =.036). Also, intrusion level trended to positively predict subsequent increase rate of avoidance symptoms (p =.059). Conclusions: This study expands previous knowledge of dynamic relations between symptom clusters during the maintenance and fluctuation of child and adolescent PTSD symptoms. By using new methodology, this study provided novel evidence for the hypothesis that intrusion symptom plays an important role in maintaining other PTSD symptoms.