Objective To study the trends and sex differences in the disease burden of preterm birth in China from 1990 to 2023, and to predict its future trajectory to inform prevention and control strategies. Methods Data from the Global Burden of Disease 2023 database were used to assess trends in incidence, mortality, and disability-adjusted life year (DALY) rates of preterm birth from 1990 to 2023. Joinpoint regression analysis was used to identify turning points in the temporal trends, and a GM(1,1) model was applied to forecast future incidence rates. Results In 2023, there were 645 000 preterm births and 6 000 deaths in China, resulting in 1.33 million DALYs. Compared with 1990, the incidence rate, age-standardized mortality rate, and age-standardized DALY rate decreased by 31.3%, 91.4%, and 87.2%, respectively. The decline in the incidence rate slowed notably after 2001, and the decline in the DALY rate weakened during 2020-2023. From 1990 to 2023, males in China consistently had higher incidence rate, age-standardized mortality rate, and age-standardized DALY rate of preterm birth than females. The GM(1,1) model predicts that the incidence rate of preterm birth will decline slowly from 7 172.6 per 100 000 in 2024 to 6 999.3 per 100 000 in 2040. Conclusions The disease burden of preterm birth in China shows a long-term decline, but the pace has recently slowed; over the next few years it is expected to remain on a slow downward trajectory, with a persistently higher burden in males than in females.