Phenology shifts over time is known as "canary in the mine" when studying the response of terrestrial ecosystems to climate change, and increasing global climate change has renewed widespread interest in plant phenological research. With the development of observational techniques, the phenological observation data collected at various spatial and ecological scales are rapidly accumulating. Although phenological changes have been observed at multiple scales (species, community, and landscape scale), the mechanisms of phenological changes are still poorly understood. In order to improve the understanding of plant phenology, in this review article, we briefly reviewed the development of plant phenology research in China and abroad; summarized the progress of phenology data collection technology and the major trend of global phenological change; summarized the mechanism and driving factors of plant phenological change; and discussed the main direction of phenological models research and phenology response to climate change. With the increasing application of phenological observation techniques at different scales, phenological research has entered a new phase. In the future, phenological research requires the development of standardized observational guidelines across regions, the integration of all relevant disciplines, the improvement of phenological models, and expansion of research areas. At the same time, it is necessary to integrate effective historical phenological data, and adopt new technologies and long-term collected phenological data to provide the basis for plant phenological research in the era of big data.