New reconstruction soil is in an unstable state, and just is the reconstruction of farming plots. In this paper, a field scouring experiment, designed as three scouring inflow rates (5, 15 and 30 L/min) and six different field widths (5,10,20,30,40,50 m), was conducted in farming reconstruction soil in hilly-mountainous region of Chongqing, in order to explore the characteristics of runoff and sediment and hydrodynamic parameters. The results showed: (1) During the scouring process, the trend of runoff rate was the fluctuated increasing period - stable development period. The trend of sediment yield rate was the fluctuated period – decrease - stable development period. (2) Hydrodynamic parameters, the mean rate values under the stable condition, and cumulative runoff and sediment yield increased with increasing scouring inflow rate. The effect of runoff and sediment yield and hydrodynamic parameters were different under different scouring inflow rates with different field width. The runoff and sediment yield fluctuated with the increase of field width. Under the scouring inflow rates of 30 and 15 L/min, the fluctuation was relatively large, and under the small scouring inflow rate (5 L/min), which was relatively slow. (3) The cumulative sediment yield increased with the increasing cumulative runoff yield, and there was a significant linear relationship between them (p<0.01). The sediment yield was affected by all hydrodynamic parameters, of which runoff power was the most important. The scouring inflow rate was positively related to the runoff and sediment yield and hydrodynamic parameters. The influence of field width was more complex, and the field width range of 20 and 30 m is the critical of new reconstructed soil erosion at slope 10°. In conclusion, the scouring inflow rate and slope width are both the driving forces of the new reconstructed soil erosion under farming plots reconstruction in hilly-mountainous region.