The invention belongs to the technical field of molecular breeding of cotton and discloses an SNP molecular marker associated with fiber strength of upland cotton as well as detection and application thereof. The SNP molecular marker is obtained by taking stable RIL group of cotton as the material through a genome resequencing method. When the SNP markers are used for carrying out molecular marker-assisted breeding selection, the breeding period can be greatly shortened; the breeding efficiency of the cotton can be improved; the cotton fiber strength can be improved.