The invention discloses application of a differential agency technology to A.G base substitution cell enrichment. A differential agency technology carrier includes esgRNA with the target sequence targeting a target gene, sgRNA with the target sequence targeting a screening reagent resistance gene with the function loss, an A.G base substitution system and the screening reagent resistant gene withthe function loss; and under guiding of the sgRNA with the target sequence targeting the screening reagent resistance gene with the function loss, the A.G base substitution system can make the function of the screening reagent resistance gene with the function loss be recovered by conducting A.G base substitution on the target sequence of the screening reagent resistance gene with the function loss. A.G base substitution cell enrichment at the cell level is achieved, and the A.G base substitution efficiency is greatly improved.