The invention discloses a spray-sowing slope protection structure for a steep rock side slope. The spray-sowing slope protection structure is composed of a supporting reinforcing assembly and planting matrix, wherein the supporting reinforcing assembly comprises a galvanized iron wire mesh, planting strips, an active protective net and an anchor rod; the galvanized iron wire mesh is suspended on the slope surface of a side slope; the planting strips are long-strip bags which are sewn by non-woven fabrics, and planting soil mixed with a fertilizer are contained in the long-strip bags; the long-strip bags are alternated and horizontally arranged along the slope surface, and are tied on the galvanized iron wire mesh by iron wires; the active protective net is laid and suspended outside the planting strips; and the active protective net is fixed on the slope surface by virtue of the anchor rod. The planting matrix is a mixture of soil, organic substances, a binder, a fertilizer, a water-retaining agent, a PH regulator and plant seeds, is prepared by uniformly stirring the mixture, and is sprayed on the slope surface with the planting strips; and the planting matrix is 10 cm thick. A setting method for the slope protection structure comprises the following steps: renovating the slope surface, laying and hanging the galvanized iron wire mesh, laying the planting strips, laying and suspending the active protective net, and spraying the planting matrix. According to the spray-sowing slope protection structure, a side slope reinforcement and protection technology and a green protection technology are organically combined together to achieve the effects of preventing rockfall, guaranteeing side slope stability, afforestation and environmental protection.