The invention discloses a method for quickly detecting a prolificacy FecB gene in sheep. The method for performing FecB genotyping by utilizing four single-stranded amplification primers comprises the following steps of: amplifying the genome DNA of the sheep to be detected simultaneously by using a specific upstream primer F1, a specific downstream primer R1, a control upstream primer F2 and a control downstream primer R2, and performing electrophoretic analysis on polymerase chain reaction (PCR) amplification products to determine the sizes and number of bands in the sequence-based amplification products, wherein the products may be 220bp and 120bp, 220bp and 160bp or 220bp, 160bp and 120bp. The research results of the invention show that Tetra-primer ARMS-PCR has the characteristics of high speed, simplicity, convenience, low cost and the like for the detection of the FecB gene in the sheep, provides theoretical and practical bases for researches and sheep breeding and brings benefits to sheep producers.