Porous eco-concrete is an alternative for the conventional concrete materials for slope protection, which could effectively protect the ecological environment of the slope in the service area during the field applications, with significant ecological and social benefits. In this paper, the key control methods of alkaline environment in porous eco-concrete for slope protection were studied by means of biogenic energy, durability test and microscopic mechanism analysis. The results demonstrate that the composite alkali-reduction method can achieve a good alkali reduction effect; the porous eco-concrete for slope protection after alkali reduction treatment has a good match with ryegrass and tall fescue and meets the growth requirements of vegetation; after plants’ growth, the compressive strength and porosity of specimens are not significantly changed. In summary, the proposed alkaline environment-modification method and vegetation matching technique could contribute to the performance improvement of porous eco-concrete, which will promote the engineering applications of “green-sustainable” eco-concrete in projects for slope protection.