Background The association between childhood adversity and an individual’s health in later life has been extensively studied in Western societies; however, little is known about this association for the development of multimorbidity in China. Methods Three waves (2011–2012, 2013 and 2015) of the China Health and Retirement Longitudinal Study were used for adults aged 45–101 years. Multimorbidity was assessed by the summed scores of self-reported physician diagnoses of 14 chronic diseases. Childhood adversity was measured by the incidence of childhood abuse and neglect, negative caregiver’s characteristics and low socioeconomic status. Latent growth curve modelling was used to investigate the trajectory of multimorbidity by childhood adversity. Results Parental physical abuse was associated with increased number of chronic diseases (intercept: 0.119; 95% CI: 0.033 to 0.205 for men and 0.268: 95% CI: 0.188 to 0.348 for women) and a higher rate of increase (slope: 0.013: 95% CI: 0.000 to 0.027 for men and 0.022: 95% CI: 0.008 to 0.036 for women) in multimorbidity. Adequacy of food was associated with a lower number chronic diseases at baseline (men: −0.171: 95% CI: −0.245 to -0.097; women: −0.223: 95% CI: −0.294 to -0.152) and a slower rate of change in multimorbidity (men: −0.015 per year: 95% CI: −0.027 to -0.003; women: −0.012 per year: 95% CI: −0.024 to -0.001). Conclusions The results demonstrate that childhood adversity exerts long-lasting effects on multimorbidity among older adults in China. Prevention of childhood maltreatment may delay or even avert the emergence of multimorbidity in later life.