In order to understand soil and water loss and its dynamic changes in the black soil region,the dynamic characteristics and causes of soil and water loss during aperiod of 50years(1950,1980and 2000)were analyzed in Heilongjiang Province,by investigating the historical information,small watershed survey,and remote sensing data analysis.The results indicated that:(1)The area of soil and water loss increased by 2.08×10⁴ km² in the past 50years,and water erosion contributed the most for the erosion.(2)During the period from 1950to 1980,the area of soil and water loss was 411.9km²,while it was 386.4km² during the period from 1980to 2000.(3)The number of erosion gully increased 98 832during the past 50years,the area of erosion gully increased by 172.4%,and the density of gully increased by 2.83times.The deterioration of soil and water loess was attributed to the uncontrolled anthropic activities,policy direction by local government and deterioration of black soil physical properties in this region.