BACKGROUND: The long-term treatment of myasthenia gravis (MG) and impaired productivity related to physical decline incur significant economic burdens on affected populations and society. This study aims to evaluate the costs of MG in China from a societal perspective and to identify the cost-driving factors. METHODS: A web-based survey was conducted on 1020 MG patients recruited through a national registry system in China. Respondents reported their socio-demographic and disease-related information and annual expenses related to MG under direct medical and non-medical costs. Indirect costs were estimated among 268 working respondents based on hours of missed work and their annual income. Generalized linear models were used to identify factors associated with different categories of costs. RESULTS: Among all respondents, the median annual direct medical cost was US219.0, with a median of 860.2 contributed by medical costs and a median of 48.2 by non-medical costs. Higher education, unemployment, hospitalization, use of mechanical ventilation, and use of multiple medications were significant driving factors of direct medical and non-medical costs. Among respondents who are at least part-time employed, the indirect costs were generally minimal. Older age, physical burden of disease, and use of multiple medications were significant predictors of higher income loss. CONCLUSION: Population with MG in China reported heavy economic burdens related to medication. Disease severity is a major driving factor of both direct and indirect costs. Targeted policies are needed to alleviate the financial burden of MG on patients and society at large.