Complex posttraumatic stress disorder (CPTSD) is widely comorbid with depression. However, how CPTSD and depressive symptoms interact with each other at the within-person level remains unclear. The current study aimed to conduct a random intercept cross-lagged panel model (RI-CLPM) to explore how depressive and CPTSD symptoms interact with each other during two years among de facto unattended children in China. We collected 4-wave data from 403 de facto unattended children in China over 2 years. The RI-CLPM was conducted to explore the longitudinal relationship between depressive symptoms, PTSD and disturbances in self-organization (DSO) symptoms of CPTSD. The results revealed that (a) depressive symptoms significantly predict PTSD symptoms and DSO symptoms, but CPTSD symptoms did not predict depressive symptoms at the within-person level, and (b) depressive symptoms were stronger predictors of DSO symptoms of CPTSD than PTSD symptoms. Our study suggests that depressive symptoms play a dominant role in maintaining the development of CPTSD among children. Furthermore, DSO symptoms of CPTSD play a key role in the maintenance of comorbid depression and CPTSD. In clinical settings, treating depressive symptoms as a priority target in interventions may improve the effectiveness of interventions for comorbid depression and CPTSD.