Abstract: Flowering represents a major physiological developmental transition from vegetative to reproductive development in the plant life cycle. It is the central cue in plant development and is determined by the control of both intrinsic genetics and environmental factors such as low temperature and photoperiod. Many genes related to flowering have been isolated in Arabidopsis, and a genetic network of the flowering process has been mapped. Histone methylation plays an important role in the regulation of plant development. Great progress has been achieved with histone modification in regulating flowering. This paper reviews the epigenetic research into histone lysine methylation in plant flowering. We also review new directions and expectations in this research field.