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To promote both accuracy and effectiveness of meteorological service for preventing fruit tree freezing injury at blooming stage and reduce economic loss, field experiments and investigations were conducted to decide the warning indexes of different grades for fruit tree freezing injury by means of the meteorological data from 1961 to 2000 from 30 stations and phenological data from 2001 to 2006 from 9 stations: serious low temperature and freezing injury (less than －2 ℃), low temperature and freezing injury （－2 ℃ to 0 ℃）, chilling injury (0 ℃ to 2 ℃).The characteristics of interannual variation and the temporal and spatial distribution of fruit tree freezing injuries at blooming stage in the major fruit planting areas are analyzed. The freeze injuries appeared most frequently in Yan’an and the western part of Weibei. Averagely, there are 4.1 to 6.3 low temperature and freezing injury days,and 3.2 to 6.0 serious low temperature and freezing injury days per year. The injures happened most likely in April. Some countermeasure for preventing damages are presented based on the experiments and analysis.