Soil and water conservation effect and the filaments runoff and sediment reduction mechanism of continu- ous spraying filaments and fixing soil planting technology on simulated slopes under heavy rainfall and flow scouring was studied based on simulation experiments with four planting layer thickness and three gradients. And the appro- priate planting layer thickness in each gradient was proposed. The results showed that spraying filaments planting subjected filaments to heavy rainfall can effectively combat the loss of vegetation layer in the early lack of vegetation cover, through effectively reduce raindrop splash and abatement runoff kinetic energy, and reinforced reinforce- ment effect together to improve the erosion resistance of vegetation. The appropriate spraying planting layer thick- ness which could be resistant to the local maximum rainfall intensity under the condition of the 30~ side slope should be maintained at more than 3 cm; and about 6cm was the appropriate thickness for the 45; for 60slope, the suitable thickness of the planting layer should be maintained at more than 6 cm.