High-resolution stable isotope records of precipitation are crucial for our understanding about the mechanism of isotope variations during typhoon precipitation events. Here we present hourly-resolution stable isotope time series of precipitation during the Typhoon In-Fa (2021) in Kunshan and Yangzhou, located in the lower reaches of the Yangtze River in Eastern China. Precipitation δ18O in Kunshan and Yangzhou ranged from -1.3‰ to -12.3‰ and -2.8‰ to -17.1‰, respectively. Both δ18O time series have shifted to more negative values as the typhoon approached. The evolution of precipitation δ18O during the typhoon is likely caused by a combination of Rayleigh distillation and microphysical processes. Precipitation δ18O values in Yangzhou are more negative than those in Kunshan with a lag of approximately 14 hours. This was mainly controlled by further continuous rainout processes during the movement of the Typhoon In-Fa from Kunshan to Yangzhou and higher condensation efficiency. This study improves our understanding about underlining mechanisms of stable isotope changes during the typhoon precipitation.