This study investigated the trajectories in posttraumatic growth (PTG) among adolescents who survived from the Yancheng tornado in China, and explored the effects of posttraumatic stress symptoms (PTSS) on these trajectories. Participants (n = 246) finished 4 assessments at 6, 9, 12, and 18 months after the tornado. Growth mixture model and logistic regression were used to examine the heterogeneous trajectories and the role of PTSS for differentiating trajectories respectively. Two latent PTG trajectories were observed: group with decreasing PTG and group with fluctuant PTG, which might stem from the illusory component and the factual component of PTG respectively based on the two-component model; and adolescents with more PTSS had higher probabilities generating decreasing PTG, that is, illusory PTG. This study suggested differentiating PTG trajectories and related influencing factors to improve the post-disaster psychological interventions in a longitudinal perspective.