Croplands under rainfall were used as test fields to analyze changes of soil particle size distribution and nutrient loss before rainfall and after rainfall.Change characteristics of sediment particle size distribution and its nutrient were discussed.The results have shown that after rainfall the clay and silt contents of the surface soil decreased and the sand contents increased in watermelon land and rape land.The nutrient contents of the surface soil declined

and the declined rate were deferent in different forms in watermelon land and rape land

among which the declined ratio of the hydrolysable nitrogen(9.67% and 7.99%) and rapidly available phosphorus(9.50% and 8.76%) was obvious

while total nitrogen(2.17% and 1.54%) lower and total phosphorus lowest.The contents of clay

silt and nutrient of sediment decreased approximately with time change

and the direct correlations were close among the contents of clay and silt and the contents of nutrient.Clay enrichment and nutrient enrichment occurred in sediment

but the enrichment ratio was different: Clay was 1.23 in watermelon land and 1.20 in rape land

total nitrogen and rapidly available phosphorus was higher than 1.3

and total phosphorus and hydrolysable nitrogen was 1.1~1.3.