Abstract: Phenology and floral differentiation morphology of the seedless honey pummelo were studied. It was found that the plant growth could be divided into germinating, budding, early flowering, blooming, withering, first physiological fruit dropping, second physiological fruit dropping, fruit ripening, and new shoot growing phenophases. The differentiation of flower buds started from mid-to-late December to mid-to-late January in a year with seven distinct periods of undifferentiation, initial differentiation, calyx differentiation, petal formation, stamen differentiation, pistil differentiation, and ovary formation.