Abstract: 【Objective】 Investigating the species of ice nucleation active bacteria (INA bacteria) and their distribution and dynamics evolution throughout the whole year plays an important role in preventing from or alleviating late frost damage on the yield in apricot. 【Method】 The species of INA bacteria and their distribution were studied on 27 apricot cultivars of Prunus armeniaca and on P. ansu while dynamics evolution throughout the whole year was investigate on ‘Yubada’ in an orchard in Haidian District. The species of INA bacteria were identified based their morphological characteristic and physiological and bio-chemical response, and the ice nucleation activity was determined based on Vali method. 【Result and conclusion】Twenty-two strains of INA bacteria, isolated from apricot trees in Beijing, were identified as three species belonging to two genera：10 strains of Pseudomonas syringae.pv.syringae，9 strains of Pantoea agglomerans，3 strains of Pantoea ananas pv.uredovora, accounting for 45.5%，40.9%，13.6% of total amount，respectively. P. agglomerans was first discovered as a kind of INA bacteria on apricot trees. The distribution and frequency of INA bacteria varied with geographic position, ecological conditions, and organs of apricots. There were three peaks of INA bacteria population throughout the year during flowering (end of March to beginning of April)，rapid fruit growth (May to beginning of June) and early stage of overwintering in December.

Key words: INAbacteria Apricot Identification Bacterial population evolution Frost