The invention relates to a plant growth inhibitor for a stereoscopic green wall. The plant growth inhibitor is a mixed drug preparation containing lodging resistant and plant strengthening drugs, and a nutrient element solution, a lodging resistant drug and a chlormequat drug are contained. By the adoption of the plant growth inhibitor for the stereoscopic green wall, the growth of plants in the stereoscopic green wall can be inhibited, the plants are prevented from excessive growth, the trimming and maintenance costs are reduced, nutrient elements needed by the plants can be further provided, and the good growth conditions of the plants are ensured.