In the context of global climate change, the variation of stable hydrogen and oxygen isotopes during rainfall is of great significance to study of the rapid surface-to-subsurface hydrologic processes in karst areas. We measured the hydrogen-oxygen isotope composition of water samples during the inter-annual scale rainfall from 2013 to 2018 and eight typical rainfalls (heavy rain to extremely heavy rain) from 2019 to 2020 in the karst area of northwest Guangxi. We also analyzed the variation characteristics of hydrogen-oxygen isotope and its influencing factors. The results show that the δD, δ¹⁸O, and d-excess in the summer half-year is significant (P<0.05) lower than the winter half-year. Hydrogen and oxygen isotopes stable in precipitation have anti-temperature effect and rainfall effect, that is, δ¹⁸O value has a significantly (P<0.001) negative linear relationship with temperature and a significantly (P<0.001) positive linear relationship with rainfall. In the process of rainfall, the rainfall effect was only observed in the long-duration (> 9.5 h) rainfall events. Extremely heavy rain does not have a rainfall effect and is related to atmospheric or geographical factors. These results suggest that studies on eco-hydrological processes should focus on the various characteristics of stable hydrogen and oxygen isotopic compositions of precipitation at different time scales.