Background and Aims Aortic aneurysm, a major cardiovascular disease with high mortality and disability rates, has emerged as a critical global public health challenge. Elevated body mass index (BMI) has been confirmed as an independent risk factor for aortic aneurysm. However, the long-term trends and heterogeneity of the disease burden attributable to high BMI in China-across sex, age, and region-remain insufficiently studied. This study, based on the Global Burden of Disease (GBD) database, aimed to analyze the changes in the disease burden of high BMI-related aortic aneurysm in China from 1990 to 2021 and compare these trends with those in global and socio-demographic index (SDI)-stratified regions.Methods Data from GBD 2021 were used to extract mortality rates and disability-adjusted life years (DALY) due to aortic aneurysm attributable to high BMI in China from 1990 to 2021. Age-standardized mortality rate (ASMR) and age-standardized DALY rate (ASDR) were calculated. Long-term trends were assessed using the estimated annual percentage change (EAPC) and Joinpoint regression models. An autoregressive integrated moving average model was applied to project trends from 2022 to 2036.Results During the study period, deaths and DALY from aortic aneurysms attributable to high BMI in China increased nearly sevenfold. ASMR rose from 1 to 3 per 100 000 population (EAPC=3.91), and ASDR increased from 23 to 74 per 100 000 (EAPC=4.11), both showing a marked upward trend. Males consistently bore a higher burden across all age groups, particularly among those aged ≥65 years. Decomposition analysis revealed that the increased burden in males was mainly driven by epidemiological improvements, while that in females was primarily attributable to population aging. Compared with the United States and global trends, China exhibited a faster increase in high BMI-related aortic aneurysm burden, which is projected to remain elevated over the next 15 years.Conclusion The disease burden of aortic aneurysm attributable to high BMI continues to rise in China, with pronounced differences across sex and age. Targeted weight management, health interventions, and early screening strategies are urgently needed for high-risk populations to curb the upward trend and optimize public health resource allocation.