Background and Objective: Multimorbidity, the presence of two or more mental or physical chronic non-communicable diseases (NCDs), is a major challenge for the health system in China, which faces unprecedented aging of its population. To examine the prevalence and trends in multimorbidity among Chinese adults since 1998. Methods: Studies regarding the prevalence of multimorbidity in Chinese people published since 1998 were searched in databases of CNKI, Wanfang, and PubMed, and so on. Meta-analysis was performed to calculate the pooled prevalence of multimorbidity based on random effects. Subgroup or Meta-regression analysis was conducted based on survey time, sex, areas, residence place, education level, marital status, and study quality. Results: A total of 123 papers were included in the analysis, with 7 714 313 participants. The pooled prevalence of multimorbidity in Chinese people was 36.3% (95%CI:32.8% ~ 39.9%). The pooled prevalence was higher in urban than in rural Chinese, and higher in women (36.2%, 95% CI:33.8% ~ 38.5%) than men (33.2%, 95%CI:30.9% ~ 35.5%), but the differences were not significant (P＞0.05). Between 1998-2019, the increase in multimorbidity did not follow the linear trend. Before 2004, the average prevalence showed 14.5%, with an annual increase rate of around 1.3%. Since 2014, the prevalence of multimorbidity was significantly higher than before (P＜0.001). Age group difference was found (P＜0.001), where the prevalence of multimorbidity for Chinese aged 60-79 years old was 38.1% (95%CI: 34.6% ~ 41.5%), followed by those aged 80 years and older, 40-59 years old, and younger than 40 years old. Conclusions: The prevalence of multimorbidity in Chinese has been rapidly increasing since 2014, and is higher in those aged 60 to 80 years than in other age groups. Therefore, efforts and preventive strategies should be adopted for early screening of multimorbidity in high-risk groups.