The invention discloses a high-steep slope plant cultivation method. 5-10cm thick ecological concrete is cast on a high-steep slope surface and prepared by the following steps: mixing and stirring gravels, cement, silica micro-powder or coal ash, water reducers, water, turfy soil and diammonium hydrogen phosphate according to the weight ratio of (1400-1800):(200-350):(20-50):(2-6):(40-90):(3-20):(0.5-5); laying grass knot nets on the slope surface, holding iron wires into U shapes, fixing the grass knot nets onto the ecological concrete, fixing plant seeds onto the ecological concrete by the iron wires, supplementing water and covering the slope surface with non-woven fabrics; removing the non-woven fabrics after germination, and applying fertilizers once every 5-7 days. Slope soil can be effectively fixed, ecological environments are improved, harm to plant roots and stems at the growth stage caused by rain wash can be effectively prevented, plant cultivation success rate is greatly increased, the vegetation coverage rate of a slope is increased, and desertification and water and soil loss can be prevented.