Abstract: In view of the problems existing in the ecological restoration of rock slope, such as the slide of the soil substrate, the serious loss of the surface soil and the poor growth of vegetation, etc., in this paper, polyurethane organic polymer materials and soil are used to form a polyurethane composite substrate. The strength, erosion resistance and vegetation growth of the composite substrate are studied through laboratory tests. In addition, a suitable site is chosen for field test to verify the effectiveness of the polyurethane composite substrate. The specific research results show that the existence of the polyurethane organic polymer has a significant effect on the strength and anti-scour of the composite substrate, and with the increasing concentration of the polyurethane organic polymer, the strength and anti-scour of the polyurethane composite substrate also increase. Compared with the specimens not added, the strength of 1% polyurethane composite substrate is 113.63 kPa, with an increasing rate of about 95.45%. The peak scouring amount of 20% polyurethane composite substrate is 28.8 g, with a decreasing rate of about 71.2%. The polyurethane organic polymer can effectively improve the germination and growth of vegetation seeds. When the concentration of polyurethane increases from 0% to 10%, the germination rate of seeds increases from 12% to 68%. When the concentration of the polyurethane organic polymer is too high, it will inhibit the germination and growth of vegetation. The polyurethane composite substrate can effectively repair the rock slope, and the effect is significant. The research results may provide some references for the ecological protection of rock slope, and are of important theoretical and practical significance.