To understand the future trajectory of health expenditure in China if current trends continue and the estimated impact of reforms, this study projected health expenditure by disease and function from 2015 to 2035. Current health expenditure in China is projected to grow 8.4 percent annually, on average, in that period. The growth will mainly be driven by rapid increases in services per case of disease and unit cost, which respectively contribute 4.3 and 2.4 percentage points. Circulatory disease expenditure is projected to increase to 23.4 percent of health expenditure by 2035. The biggest challenge facing the Chinese health system is the projected rapid growth in inpatient services. Three percent of gross domestic product could be saved by 2035 by slowing the growth of inpatient service use from 8.2 percent per year in 2016 to 3.5 percent per year in 2035. Health expenditure in 2035 could be reduced by 3.5 percent if the smoking rate were cut in half and by 3.4 percent if the high blood pressure rate were cut by 25 percent. Future action in controlling health expenditure growth in China should focus on the high growth in inpatient services expenditure and interventions to reduce risk factors.