Objective To explore the trajectory of changes in maternal family functioning from early pregnancy to 12 months postpartum and the factors that influence it. Methods A total of 1,053 pregnant women were conveniently selected from two maternity and child health centres, and family functioning was investigated by using the Family Care Index Questionnaire in early pregnancy, mid-pregnancy, late pregnancy, and 1, 3, 6 and 12 months postpartum, and by using the Edinburgh Postnatal Depression Inventory in early pregnancy to investigate prenatal depressive symptoms. A latent class growth model was used to analyse the trajectory of maternal family functioning, and multiclassified logistic regression was used to analyse the influencing factors of different trajectories. Results A total of 689 pregnant women completed the full follow-up. Maternal family functioning was classified into the group with continuous decline of moderate-to-severe impairment （12.3%）, the group with fluctuating decline of moderate impairment（44.9%）, and the group with no impairment and stable good functioning（42.8%）; maternal literacy, whether she was a single child or not, and the presence of depression in early pregnancy were the factors influencing the trajectory of family functioning (all P<0.05). Conclusion There is heterogeneity in the trajectory of maternal family functioning from early pregnancy to 12 months postpartum. Different subtypes of mothers should be identified in time, and targeted measures should be taken according to the influencing factors in order to improve maternal family functioning.