Excessive growth in health expenditure has led to a continuous increase in the burden of medical care for residents, and how to deeply analyze the key factors affecting the growth of health expenditure has become a topic of public concern. We aim to analyze the causality and pathways of complex factors on health expenditure in different environments. We screened and analyzed the key factors affecting China’s health expenditure during the period of 2012-2021 through structural equation modeling and explored the path coefficients between latent and observed variables by dividing the key factors into three dimensions: the ecological environment, the social environment, and the medical environment using exploratory factor analysis in order to quantify their degree of influence. The results show that: (1) the social environment has a positive effect on the growth of China’s health expenditures, while the medical environment and the ecological environment have a negative effect on China’s health expenditures; (2) the medical environment has the greatest degree of influence on China’s health expenditures, followed by the social environment and the ecological environment; and (3) among the three dimensions, firstly, the social environment and the medical environment have the highest degree of correlation, then the ecological environment and the social environment, and lastly, the medical environment and the ecological environment. Overall, China has improved the medical environment by increasing support for the health sector while mitigating the continued growth of health expenditure. This implies that the synergistic effects of complex factors in different environments should be taken into account when analyzing the factors affecting the growth of health expenditure to improve the health environment for the population and realize the sustainable development of China’s health sector.