Paired box 7 (PAX7) gene regulates the conversion of muscle satellite cells into myogenic cells and participates in multi-step processes in myogenesis.Expression levels of PAX7 are decisive for its regulatory function. Previous reports revealed that PAX7 were responsible for the developmental traits of muscle. The relationship of the PAX7 promoter variants and livestock phenotypic traits has not been fully elucidated. We detected a novel 10-bp insertion/deletion (indel) polymorphism in the bovine PAX7 promoter and revealed that the indel altered the binding of the transcriptional factor ZNF219. Luciferase reporter assay showed that deletion-deletion (Del-Del) genotype of the PAX7 gene showed 2.79-fold higher promoter activity than the insertion-insertion (Ins-Ins) genotype (P < 0.05), and ZNF219 overexpression significantly diminished the luciferase activity in Ins-Ins groups. Moreover, the expression of PAX7 and its down-stream genes were detected in fetal skeletal muscle of cattle with different PAX7 genotypes, where the Del-Del genotype also displayed high expression levels. Statistical association analysis demonstrated that this indel had significant effects on early growth traits in cattle. These findings provide a complete overview of the function of the PAX7 10-bp variant, which may have potential as a genetic marker for marker-assisted selection in improving economically significant traits of cattle.Cattle phenotypes of economic significance, such as growth rates, carcass, and meat quality, have attracted much attention from breeders in the beef cattle industry. Such phenotypes constitute a multifactorial background that arises from interactions between environmental and genetic factors 1 . In marker-assisted selection programs, the efficiency of selection is associated with the identification of candidate genes, as well as the exploration of genome-wide variation markers that are responsible for the complex quantitative traits 2 . The establishment of genetic association approach provides a unique opportunity to study genotype-phenotype relationships 3 . Therefore, the integration of screening for variations and gene association programs can improve assessments of the genetic effects of candidate genes, thus providing promising materials for successful genetic selection in cattle breeding.Muscle satellite cells, known as muscle-specific committed progenitors, are located under the basal lamina of muscle fibres and play important roles in the growth, maintenance, homeostasis, repair, and regeneration of skeletal muscle [4][5][6] . Paired box 7 (PAX7) gene, a member of the paired box gene family, is the marker gene of myogenic satellite cells 7 . PAX7 is specifically expressed in quiescent, activated, and proliferating satellite cells, and PAX7-expressing satellite cells are indispensable for the postnatal muscle development and regeneration after the injury of skeletal muscle, however, their regenerative function can not be performed by other endogenous cell