Ambient ozone (O3) pollution has become a big issue in China. Recent studies have linked long- and short-term O3 exposure to several public health risks. In this study, we (1) characterize the long-term and short-term O3-attributed health metric in China from 2015-2019; (2) estimate the surface O3 trends; and (3) quantify the long-term and short-term health impacts (i.e. all-cause, cardiovascular and respiratory mortality) in 350 urban Chinese cities. In these 5-years, the national annual average of daily maximum 8h average (AVGDMA8) O3 concentrations and warm-season (April−September) 4th highest daily maximum 8h average (4DMA8) O3 concentrations increased from 74.0±15.5 μg/m3 (mean±standard deviation) to 82.3±12.0 μg/m3 and 167±37.0 μg/m3 to 174±30.0 μg/m3 respectively. During this period, the DMA8 O3 concentration increased by 1.9±3.3 μg/m3/yr across China, with over 70% of the monitoring sites showing a positive upward trend and 19.4% with trends >5 μg/m3/yr. The estimated long-term all-cause, cardiovascular and respiratory premature mortalities attributable to AVGDMA8 O3 exposure in 350 Chinese cities were 181,000 (95% CI: 91,500-352,000), 112,000 (95% CI: 38,100-214,000) and 33,800 (95% CI: 0-71,400) in 2019, showing increases of 52.5%, 52.9% and 54.6% respectively compared to 2015 levels. Similarly, short-term all-cause, cardiovascular and respiratory premature mortalities attributed to ambient 4DMA8 O3 exposure were 156,000 (95% CI: 85,300-227,000), 73,500 (95% CI: 27,500-119,000) and 28,600 (95% CI: 14,500-42,800) in 2019, increases of 19.6%, 19.8% and 21.2% respectively compared to 2015. The results of this study are important in ascertaining the eﬀectiveness of recent emission control measures and to identify the areas that require urgent attention.