The invention relates to a plant growth regulation complexing agent for strengthening perennial ryegrass to restore cadmium-polluted soil and application of the plant growth regulation complexing agent. The plant growth regulation complexing agent is prepared from the following raw materials: 12.5 to 41 parts of polyamine, 4 to 41 parts of salicylic acid, 8 to 60 parts of sodium nitroprusside, 0.8 to 10 parts of sodium selenite, 50 to 75 parts of Tween and 100000 to 150000 parts of water. A traditional single exogenous plant growth regulating substance is broken through, the plant growth regulating complexing agent is compounded by various exogenous substances including polyamine, salicylic acid, sodium nitroprusside and sodium selenite, various exogenous substances are organically combined, the enrichment rate of ryegrass to cadmium can be increased, the cadmium content of ryegrass can be increased, and the cadmium content of ryegrass can be increased. Meanwhile, the capability of the ryegrass on stress of other organisms and abiotic organisms is enhanced, and the problem that the biomass of the ryegrass is small is solved. The plant growth regulating complexing agent is used for strengthening the perennial ryegrass to restore the cadmium-polluted soil, the characteristics that the perennial ryegrass is harvested for multiple times in one year and the harvesting interval is short are fully utilized, the time for phytoremediation of the cadmium-polluted soil is shortened, and the cadmium pollution level in the soil is reduced.