Rainfall and runoff are the main dynamic factors which cause soil erosion on the Loess Plateau.Research on processes of rainfall,runoff and sediment yield can serve as development of process-based mode of soil erosion,soil and water conservation,and ecology construction on loess region.Based on analyzing the data of natural unsteady rainfall,runoff and sediment yield processes observed in Zizhou field experimental station,and applying non-linear modelling technology,the dynamic variational processes and responded relationship of rainfall-runoff-sediment yield on loess hillslope are studied.The research results show that the variation processes of accumulated rainfall amount with rainfall time,the variation processes of accumulated runoff depth with runoff time,the variation processes of accumulated erosion modulus with sediment yield time,the responses of variation processes of accumulated runoff depth to variation processes of accumulated rainfall amount,the responses of variation processes of accumulated erosion modulus to variation processes of accumulated runoff depth are all displayed with non-linear relationships.All of them can be divided into two types and can be described with extanded S curve model and extanded power function model respectively.