Abstract: The bulb apical bud cell ultra-structure changes of Lilium pumilum bulbs during breaking dormancy under refrigerated condition were studied. Results showed that the material and energy metabolism of bulbs were weak between 0 to 12 days and bulbs couldn’t sprout；The germination rate of bulbs was lower and mitochondria and golgi vesicles increased，cells exchanged materials through the plasma membrane endocytosis and plasmodesmata between 12 to 48 days. Nucleoli were incompact and endoplasmic reticulums scattered orderly between 48 to 72 days，and endoplasm bridges formed at the edges of vacuole membrane and plasma membrane，with some of them extending to the nuclear envelope. Intracellular and intercellular connection had been established in this period. Endoplasm bridges and the plasmodesmata connected in budding period，and the internal structures and quantity of organelles increased obviously，dormancy is completely broken in this period.

Key words: lily；bulb, cold storage, apical bud cell, ultrastructure