Abstract: The aim was to determine the best coupling between growth regulator application and high-yield planting density of sorghum. By using sorghum‘Jinza 18’as material, two-factor randomized block design was carried out with different densities and chemical control agents, and three replications were conducted. Four gradients of chemical control agents were set up. The results showed that the density of 150000 plant/hm2 was the best. The photosynthetic rates of A1B2 increased by 15.55%, 22.22% and 24.44%, compared with A2B2, A3B2 and CK. The chlorophyll content of A1B2 increased by 7.01%, 9.72% and 17.06%, compared with A2B2, A3B2 and CK. The yield of A1B2 increased by 7.66%, 9.10% and 10.19%, compared with A2B2, A3B2 and CK. The plant height of A1B2 decreased by 2.01%, 2.76% , 4.83%, 6.45%, 10.3%, 6.21%, 11.7%, 13.78%, 21.38%, compared with A1B1, A1B3, A2B1, A2B2, A2B3, A3B1, A3B2, A3B3 and CK. Under the condition of low density, flexural strength was higher than that under the high density condition. A1B2 was the best treatment. Suitable concentrations of ethephon and chlormequat could promote physiological metabolism of sorghum and enhance photosynthetic performance, and finally increase grain yield. The optimum coupling between growth regulator application and high-yield planting density of sorghum was ethylene diluted 200 times spraying and sorghum planting density of 150000/hm2.