Climate data from seventy-one meteorological stations in the soybean planting areas in three provinces of Northeast China (NEC) during 1961 to 2010 were used to calculate the reference crop evapotranspiration using the Penman-Monteith formula. Then combined with the revised crop coefficient, soybean water requirement can be obtained during each growth stage. Finally, we calculated the Crop Water Deficit Index (CWDI) by considering cumulative effects of moisture surplus condition during the soybean growing season. and obtained the degree of drought Based on this index and the degree of drought, the characteristics of spatio-temporal variation for occurrence frequency and degree of soybean drought in NEC during the study period were analyzed. Result shows that there is a significant spatial variation in the occurrence frequency of soybean drought,which was increased from east to west. Light drought is the most frequent drought, followed by the middle drought and heavy drought during the whole soybean growing season. There could be relatively higher frequency of light drought in the western regions of Heilongjiang Province and the western and southern regions of Liaoning Province. In the western regions of Jilin Province,there is relatively less frequency of light drought, but the frequencies of middle drought and heavy drought are higher. We also found the basic vegetative phase (sowing to branching) experienced the most severe drought and the frequency of drought exceed 50% (once every 2 years) at the 56% of the selected sites in the study areas,the frequency of drought exceed 80% (four every 5 years) at the 31% of the selected sites in the study areas. The drought during the panical formation phase (branching to flowering) is lighter, drought frequency was lower than 80% in most regions in the study area except Qian'an and Tongyu of Jilin Province, and drought frequency was higher than 50% (once every 2 years) at the 48% of the selected sites in the study area. The drought during the reproductive phase (flowering to maturity) is lightest, but there could be still high drought frequency (50%-80%) in the southwest regions of Heilongjiang Province,northern of Sanjiang Plain,western of Jilin Province,and western and southern of Liaoning Province. Interannual variability in CWDI differs from regions. The CWDI showed a downward trend during the sowing to branching stage in all three representatives sites. We can find a maximum inter-annual fluctuation during the branching to flowering stage, it showed a downward trend in Liaoning Chaoyang and Heilongjiang Suihua during this stage, and a upward trend in Jilin Tonghua. There is least value of CWDI during the flowering to maturity stage,and showed an upward trend in Liaoning Chaoyang and Heilongjiang Suihua during this stage; interannual variability is not significant in Jilin Tonghua. In other words,generally the drought threat is progressively more severe during reproductive phase. There is also obvious decadal variability of drought degrees during whole growing period. In 1980s, either drought degree and range were the smallest,from 2000 years,the range of medium drought and heavy drought increased significantly.