In order to study erosion rule of engineering slope runoff and provide scientific and theoretical basis for control of water and soil loss of slope in Pisha sandstone region, the hydrodynamic characteristics of slope runoff under the different EN—1 soil stabilizer contents, curing ages and compaction degrees treated with soil stabilizer were studied by using indoor runoff scouring experiment. The results showed that flow velocity of slope runoff of Pisha sandstone stabilized soil increased with the increase of soil stabilizer contents, curing ages and compaction degrees under the soil stabilizer contents, curing ages and compaction degrees in this experiment and it had a fluctuant and decreased tendency with scouring time. The Reynolds number (Re) of slope runoff decreased with the increase of soil stabilizer contents, curing ages and compaction degrees and it had a fluctuant and increased tendency with scouring time. The Froude number (Fr) of slope flow runoff had the opposite trends. The flow regimes were turbulent flow and subcritical flow when scouring proceeded to the later period at smaller compaction degrees. The flow regimes were all laminar flow and supercritical flow at the other treatments. The Darcy—Weisbach drag coefficient (f) of slope runoff decreased with the increase of soil stabilizer contents, curing ages and compaction degrees, and had a positive correlation with sediment transport rate.