Phytoplankton bloom is one of the most important biological processes in coastal seas. Changes in the timing, duration and magnitude of phytoplankton blooms can affect the phenological coupling in pelagic food-webs, with important ramifications for trophic interactions, ecosystem productivities and biogeochemical processes. Phytoplankton phenology has been one of the research hot-spots in the field of biological oceanography, aiming to better understand the impact of climate change on marine ecosystem. The history and methodology for studying phytoplankton bloom, as well as our current understanding of bloom dynamics, were reviewed here. The effects of climate change on the phytoplankton bloom dynamics and recent research progresses in this field were also highlighted. The main features of the phytoplankton bloom in the coastal areas of China were examined based on a preliminary analysis of remotely sensed chlorophyll data. Future direction of phytoplankton phenology studies, with a focus in China seas, was also suggested as a prospect.