In this study, long-term changes in the East Asian summer monsoon (EASM) lifecycle during 1979 – 2017 (2010 for models) are analyzed based on observational datasets and historical simulations of the Coupled Model Intercomparison Project Phase 6 (CMIP6). According to the analysis, the active and break phases of EASM have been intensified, resulting in a shorter but stronger rainy season followed by a longer dry spell. This intensification in precipitation during the rainy period is accompanied by increased lower tropospheric southwesterly wind and subsequent convergence of water vapor flux. These changes are accompanied by the widely reported westward extension of the North Pacific Subtropical High, which has been associated with the warming climate. The performance of CMIP6 models in depicting the observed intensification of the EASM lifecycle varies and the monsoon precipitation is generally underestimated. However, some of the models did simulate the intensified EASM lifecycle similar to that observed. The result highlights the reasonable performance on EASM shown in some CMIP6 models and those simulations lend support to a warming-driven intensification of the EASM lifecycle.