目的 基于全球疾病负担研究（Global Burden of Disease Study, GBD）2021数据，分析1990—2021年中国0~19岁儿童青少年心肌炎的变化趋势，并预测2025—2050年疾病负担趋势。 方法 提取GBD 2021数据库中国0~19岁人群心肌炎发病率、患病率、死亡率及伤残调整生命年（disability‑adjusted life year, DALY）数据，采用Joinpoint回归模型分析年度变化百分比，利用GBD比较风险评估框架量化4类危险因素（环境/职业风险、非最佳温度、高温、低温），使用ARIMA模型预测2025—2050年疾病负担趋势。 结果 1990—2021年中国0~19岁儿童青少年心肌炎年龄标准化患病率上升，年龄标准化发病率、年龄标准化DALY率与年龄标准化死亡率均有所下降，中国总体疾病负担高于全球及中等社会人口学指数地区平均水平，男性疾病负担高于女性。2021年中国非最佳温度与环境/职业风险合计贡献66.4%的疾病负担，高温导致的DALY及死亡率均上升。ARIMA模型预测显示，2025—2050年中国儿童青少年心肌炎的总发病率将保持稳定，但5~9岁年龄组的DALY和死亡率预计呈上升趋势。 结论 1990—2021年中国0~19岁儿童青少年心肌炎的年龄标准化患病率持续上升，男性各项负担指标均高于女性；预测2025—2050年心肌炎的总发病率将保持稳定，但5~9岁年龄组的伤残及死亡负担将上升。需构建基于年龄-性别分级的防控体系，并将极端温度防护纳入国家儿童心血管健康战略。

Objective Based on data from the Global Burden of Disease Study (GBD) 2021, this study aims to analyze trends in myocarditis among children and adolescents aged 0-19 years in China from 1990 to 2021 and predicts the disease burden trends from 2025 to 2050. Methods Data on incidence, prevalence, mortality, and disability-adjusted life year (DALY) of myocarditis in the Chinese population aged 0-19 years were extracted from the GBD 2021 database. Joinpoint regression was used to estimate annual percent change. The GBD comparative risk assessment framework was used to quantify four categories of risk factors: environmental/occupational risks, non-optimal temperature, high temperature, and low temperature. The ARIMA model was applied to forecast the disease burden trends from 2025 to 2050. Results From 1990 to 2021, the age-standardized prevalence rate of myocarditis in Chinese children and adolescents aged 0-19 years increased, while the age-standardized incidence rate, age-standardized DALY rate, and age-standardized mortality rate decreased. The overall disease burden in China exceeded the global average and that of regions with a middle socio-demographic index. Males had a higher disease burden than females. In 2021, non-optimal temperature and environmental/occupational risks collectively accounted for 66.4% of the disease burden, and DALYs and mortality attributable to high temperature showed an increasing trend. ARIMA model projections indicate that by 2050, the overall incidence of myocarditis will remain stable, whereas DALYs and mortality in the 5-9-year age group are expected to increase among Chinese children and adolescents aged 0-19 years. Conclusions In China, the age-standardized prevalence of myocarditis among children and adolescents aged 0-19 years increased continuously from 1990 to 2021, and males had higher values across all burden metrics than females. Projections for 2025-2050 suggest that the overall incidence of myocarditis will remain stable, whereas the disability and mortality burden in the 5-9-year age group will rise. An age- and sex-stratified prevention and control system should be established, and protection against extreme temperatures should be incorporated into the national strategy for children's cardiovascular health.