<p>Childhood maltreatment often leads to higher risk of posttraumatic stress symptoms (PTSS) in emerging adults. Recently, many researchers have focused on the alleviating role of gratitude in PTSS. However, the potential bidirectional relationship and mechanisms of them remain unclear. Therefore, this study addresses this gap by employing the cognitive model of PTSD and utilizing a four-wave longitudinal design with 6-month intervals between each wave among 794 Chinese emerging adults (51.6% female; <i>M</i>_age = 19.05 [<i>SD</i> = 1.31]) with childhood maltreatment. Utilizing a cross-lagged panel model (CLPM) and a random intercepts cross-lagged panel model (RI-CLPM), we examined the longitudinal associations between self-compassion, gratitude, and PTSS. The CLPM suggested that PTSS can directly predict gratitude, and the longitudinal association between gratitude and PTSS was significantly mediated by self-compassion at the between-person level. In contrast, the RI-CLPM did not support a bidirectional association between gratitude and PTSS, as observed in the CLPM. However, the bidirectional associations between self-compassion and gratitude, as well as between self-compassion and PTSS, remained stable across both models. This underscores the importance of fostering long-term stable gratitude in conjunction with self-compassion-based interventions to alleviate PTSS in emerging adults with childhood maltreatment.</p>