The invention relates to an ecological protection method for a high steep side slope. The method mainly comprises the steps of slope surface treatment, concrete shotcrete and rock bolt support, vegetating hole arrangement, net spreading, spray material preparation, granule spray sowing, maintenance, management, and the like. In the method, guest soil materials such as humus loam rich in organic matters and clay are utilized to undergo a granule reaction after mixed with a granule agent at the moment of spray sowing so as to form a greening template which has the same high order granule structure as natural soil and strong erosion resistance and can suppress water and soil loss. After a diversified mature plant community which is in harmony with surrounding vegetation environment is formed, the slope surface can be protected, which can effectively resist diseases and insect pests and maintain the ecological balance. Post maintenance management and expenses can be saved. All used materials can be naturally degraded, have no pollution to the environment and can purify air and beautify the environment. Equipment of the method does not need to be hung on the slope surface for construction, and spray sowing operations are carried out only below the slope surface, thus the method has high construction speed and safety. The method is suitable for slope surfaces which are difficult to green, and the like, such as various high steep and unstable slope surfaces, bare slope surfaces having high greening expected values, and the like.