The invention discloses a hard reinforced concrete revetment slope biological repairing method, which is characterized by comprising the steps of: roughing a concrete revetment and constructing drainage ditches at set intervals; digging a water collecting tank on one side of the cross of the revetment and a road, reserving an opening at the joint of the drainage ditch and the water collecting tank, and constructing a watertight concrete overflow bank; filling gravels in the water collecting tank and the drainage ditches; and welding earthwork grids by high-density polyethylene stripes on the protection slope, laying gravel cushion coats in the earthwork grids, and finally pouring biological slurry. The method has the advantages that: the whole project is stable and safe; rain flows into the water collecting tank and passes through grave areas, non-watertight sand-free concrete, a slope cushion coat, plant roots and the like to seep into rivers, so water quality is improved to a relatively large extent; when rainfall runoff is overlarge, the rain overflows from the overflow bank and passes through the graves of the drainage ditches, so the water quality is also purified to a certain extent, meanwhile the slope is protected; the biological slurry poured onto the slope is prepared from biological materials, and has certain anti-erosion strength and can be used as a substrate for plant growth, so the cost is low and the operation is simple.