Under the influence of global warming, the continuously growing Marine Heatwaves (MHW) has a serious impact on the climate system and the social economy, of which the Western Pacific Warm Pool area is a typical area of MHW characteristic changes. Based on the MHW database, the National Centers for Environmental Prediction (NCEP) atmospheric and oceanic reanalysis data, the chlorophyll-a concentration data provided by the National Aeronautics and Space Administration (NASA) Aqua satellite and the biogeochemical Argo floats, by using statistical methods such as composite analysis and singular value decomposition (SVD), we explore the evolution characteristics, physical mechanisms and ecological impacts of MHW in the Western Pacific Warm Pool from 2020 to 2022. The results show that MHW properties in the Western Pacific Warm Pool region have increased significantly in the past 30 years and it is closely related to the continuous La Ni?a events. Under the background of multi-year La Ni?a events from 2020 to 2022, the frequency of MHW in the Western Pacific Warm Pool reached the highest in the world, and the coverage area, frequency, total days and cumulative intensity of MHW are the most notable since 1982. By using the mixed layer heat budget equation in the Western Pacific Warm Pool region, it is shown that the occurrence of the strongest MHW during the period 2020 to 2022 is mainly dominated by the downward shortwave radiation term in the net flux and the latitudinal advection term in the marine dynamic processes. In addition, we also revealed that the MHW properties and marine ecological indicator chlorophyll-a concentration show a negative correlation on the spatial and temporal scales in the Western Pacific Warm Pool region, especially the MHW events during 2020-2022 caused the significant decline of overall phytoplankton biomass in the upper ocean of the region.