The invention discloses a method for breeding high-quality mutton black goats through three-line hybridization. Polymorphic black goats having CSN1S genes, PRLR genes and UBA52 genes are bred by the specific breeding method, and are strictly bred according to customized standards. The method has the advantages that the dominant genes of mutton production properties, lambing properties and lactation properties are screened, and by the aid of heteroses, the reproduction properties of the Guizhou black goats are improved on the basis of individual mutton production and lactation properties and group lambing properties, so that new varieties (lines) of the high-quality Guizhou black goats are bred.