The present invention belongs to the field of rice seeds and discloses a composition for promoting the early harvest of rice seeds, its preparation method, and application. The composition is made from the following raw materials in mass percentage: Dihydromyricetin Extract 61.50% to 63.50%, Resveratrol Extract 6.00% to 9.00%, Vitamin C 12.00% to 16.00%, Agricultural Streptomycin Sulfate 12.00% to 16.00%. The composition is reasonably formulated, utilizing the respective effects of chemical raw materials and natural plant extracts to regulate the seed harvest period. Experimental verification has shown that the composition has a significant effect on promoting the early harvest of rice seeds. The preparation process is simple, and the composition is easy to use, providing an ideal product for promoting the early harvest of rice seeds.