The invention discloses a method for remarkably improving resistance of cotton to greensickness through verticillium dahlia interference VdRGS1 gene expression and belongs to the field of biological technique application. The invention provides a nucleotide sequence of a VdRGS1 gene and an ORF sequence and an amino acid sequence of cDNA. Function and phenotypic analysis shows that VdRGS1 is capable of regulating and controlling pathogenicity of verticillium dahlia, formation of microsclerotia, growth of spores and hyphae, and the like, and plays a significant role when verticillium dahlia invades and infect a host. By using a transgenic technique, a greensickness bacterium which can express green fluorescent protein (GFP) is created, by using a virus-induced gene silencing (VIGS) technique, a GFP gene of the transgenosis verticillium dahlia can be efficiently silenced in cotton, the result shows that host induced gene silencing (HIGS) is achieved on the basis of the VIGS technique, andinvading verticillium dahlia genes can be successfully silenced in cotton by using the technique. By using an HIGS technique based on VIGS, the verticillium dahlia VdRGS1 is silenced in cotton, and the resistance of cotton to verticillium dahlia is remarkably improved.