The parent‒child relationship is a crucial factor in promoting adolescent mental health. However, the current evidence on the relationship between parent‒child relationships and adolescent conscientiousness and neuroticism, as well as the directionality of these relationships, remains limited. In particular, there is a lack of analysis focusing on Chinese middle school students. Based on a sample of 8437 students from the China Education Panel Survey (CEPS) database, this study empirically examined the bidirectional relationships between parent‒child relationships, conscientiousness and neuroticism among Chinese middle school students, with specific emphasis on the significant role of parent‒child relationships in the development of conscientiousness and neuroticism. Descriptive statistical results indicated that during the seventh and eighth grades of Chinese middle school students, the closeness of their parent‒child relationships with both parents decreased, while the level of conscientiousness showed a slight decrease, and neuroticism showed an increasing trend. Correlational results demonstrated a significant positive correlation between parent‒child relationships and conscientiousness and a significant negative correlation between parent‒child relationships and neuroticism. Further analysis using cross-lagged models revealed that parent‒child relationships significantly positively predicted subsequent conscientiousness development, and conscientiousness significantly positively predicted subsequent parent‒child relationships. Parent‒child relationships significantly negatively predicted subsequent neuroticism development, and neuroticism levels also significantly negatively predicted subsequent parent‒child relationships. Based on these findings, we believe that there is a need to strengthen parent‒child relationships and to recognize the important role that both mothers and fathers play in the healthy development of their children. Both parents should actively contribute to their children's upbringing and take responsibility for their family education.