Discharge recession process is an important component of rainfall-runoff process.Analysis of recession process of overland flow under simulated rainfall on cropland of purple soil has been carried out.Results show that slope gradient and rainfall intensity have notable effects on recession flux and inverse recession duration.Recession flux increased as rain intensities increased

and reduced as slope became steeper.Recession flux and time varied significantly under different surface treatments.Under downslope cultivation

recession duration is the shortest and recession flux is the least.Recession process holds longer time and greater flux is produced on bare land.For contour cultivation

recession process lasts the longest but recession flux is less than that on the bare land.The Manning's roughness coefficient for the cropland of purple soil is then calculated by using Retention Curve method.In terms of the coefficient

the order of the three treatments are bare land(0.028)< downslope cultivation(0.065)< contour cultivation(0.071).