In order to reveal the characteristics of runoff and sediment and nutrient loss path of on steep slope caused by platform inflow of engineering soil deposits, a laboratory scouring experiment, designed to have three scouring inflow rates (1.7, 2.3, 2.9 L/min) and three slope gradients (25°, 30°, 35°), was conducted on disposal sites in opencast coal mine to research the processes of surface runoff, interflow and sediment and measure the concentration of nitrogen and phosphorus in these for calculating the nutrient loss and contribution. The results indicated as follows: Surface runoff was the main type of runoff generation in earth-covered engineering slope in eastern Inner Mongolia. With the increase of slope gradient and scouring inflow rates, surface runoff increased but interflow decreased. The sediment yield rose first and then decreased with the increase of slope gradient, and the critical slope gradient was about 30°. The loss concentrations of ammonium nitrogen and phosphate in surface runoff were higher than those in interflow, and the concentrations of nitrate nitrogen were lower when the scouring flow was larger (2.9 L/min). The loss of phosphate in runoff and nitrogen and phosphorus in eroded sediment firstly increased and then decreased with the increase of slope gradient. The loss of nitrogen and phosphorus from surface runoff and sediment increased with the increase of scouring inflow rates. The amount of nutrient loss in runoff was nitrate nitrogen > ammonium nitrogen > phosphate. Erosion sediment was always the main export route of phosphate, accounting for more than 59.69% of the total loss. The maximum nitrogen loss occurred only when the slope gradient was 30°, while on the 25°and 35°slope, surface runoff was the main route of nitrogen loss, at low inflow rates (1.7, 2.3 L/min), the nitrogen output from interflow was the second.