Abstract: Soil moisture is one of the most important indexes for drought prediction,agricultural production,crop layout and agricultural decision making.Based on the soil moisture data of twenty-six agro-meteorological observation stations in Heilongjiang Province from 1984 to 2005,with the statistical method of the climatic tendency rate and trend coefficient,the spatial and temporal characteristics of the soil moisture variation and their influencing factors in the main agricultural areas of Heilongjiang Province were analyzed.The results showed that the spatial distribution of the soil moisture was obvious different.It had positive correlation with the spatial distribution of the air temperature,and negative correlation with the rainfall spatial distribution.The soil moisture was relatively higher in Sanjiang Plain and the middle agricultural areas,while it was relatively lower in Songnen Plain.The soil moisture as a whole showed a decreased trend during 1984 and 2005.The decreasing extent of the soil moisture was different in the different seasons.The soil moisture significantly decreased in turn in autumn and in spring,while the deceased trend of the soil moisture was not obviously in summer.The study showed that the spatial distribution and change trend of the soil moisture were importantly influenced by climate,climate change and agricultural production.The drought disasters might be heavier in Songnen Plain,while the spring flood disasters might be relieved in east parts of the Sanjiang Plain.

Key words: Heilongjiang Province, Heilongjiang Province, Main agricultural areas, Soil moisture, Change trend