The invention discloses a fast detection method for chicken Pax7 gene 31 bp indel polymorphism and the application thereof, wherein the detection method comprises the following steps: designing a pair of primers based on gene sequences of a third exon and a third intron of a chicken Pax7 gene; then performing PCR amplification; and finally detecting the 31 bp indel polymorphism of the gene through agarose gel electrophoresis, when the third intron 31 bp is inserted, the gene is an II genotype, when the third intron 31 bp is in deletion, the gene is a DD genotype, and when the locus is a heterozygous individual, the gene is an ID genotype. Meanwhile, the method utilizes detection result to perform relevance analyze with chicken economical characters, which is used for chicken assistant selection and molecular breeding. According to the invention, during big DNA fragment detection, the method not only has high resolution, sensitive detection and accurate type judgment, but also has the characteristics of simplicity in operation, time conservation and low cost, and can be widely popularized.