Based on measured meteorological data obtained from 106 stations located in Northeast China, potential evapotranspiration was calculated by applying Penman-Monteith equation, and water deficit was expressed as the difference of precipitation and potential evapotranspiration at the same period. Finally, spatial and temporal variation characteristics of water deficit over Northeast China were analyzed by using Kendall rank-related trend analysis, Morlet wavelet function and Mann-Kendall abrupt test. The results showed that: 1) during the period from 1951 to 2008, multi-year average water deficit over Northeast China varied between -850 mm and 650 mm with the spatial variation pattern of decreasing gradually from east to west, from north to south and from northeast to southwest. 2) Among all the 106 meteorological stations located in Northeast China, there were 97 stations showed declining trends in yearly water deficit, and the declining trends of 28 stations could even pass the significance test at the level of P<0.05. 3) Yearly water deficits of the whole region, Hailar, Changchun and Kuandian fluctuated obviously with the multi-year average water deficit for each were -283.60 mm, -427.25 mm, -362.58 mm and 334.91 mm, and monthly water deficit of them was uneven with the minimum value appearing in May and the maximum value in July or August. 4) Yearly water deficit had periodic characteristic, water deficit of the whole region, Hailar, Changchun and Kuandian showed "higher period", "lower period" alternately with the main period of 26, 28, 25 and 9 years, respectively. Moreover, water deficit also had abrupt property as other meteorological factors, water deficit of the whole region showed an abrupt decrease in 1999, while Changchun showed two abrupt decrease events which happed in 1958 and 1998.