(Objective)The present study was conducted to investigate the skeletal muscle fiber growth and development in the high meat-quality chickens HS1 and the broilers Cobb and explore fiber growth-related gene expression characteristics in this process.(Methods)The samples were randomly collected in males of HS1 and Cobb on d 1,7,28,49,70,with 3 repliates at each time point and population in pectoralis major and gastrocnemius muscle.We compared the differences of muscle fiber development between populations,tissues,and ages,respectively,and analyzed the expression of MyoD,MyoG,IGF-1 and Pax7 genes in these samples.(Results)Our results indicated that Cobb and HS1 pectoralis major muscle and gastrocnemius muscle absolute weight and absolute fiber density increased with time,the later gradually close to zero.Conversely,their absolute fiber diameter decreased.Cobb pectoralis major muscle and gastrocnemius muscle absolute weight and absolute fiber diameter were greater than the absolute growth of HS1 chicken.Pax7 was consistent with the absolute growth trend of muscle fiber density; IGF-1,MyoG and MyoD were consistent with the trend of muscle fiber absolute diameter.MyoG and MyoD expressions in Cobbs pectoralis major muscle were the highest on d 28,compared with d 1,7,49,70; and IGF-1,MyoG and MyoD expression in Cobb and HS1 gastrocnemius muscle on d 7 with the maximal.(Conclusion)Our study suggest that MyoD,MyoG,IGF-1 and Pax7 played important roles in muscle fiber development,which provided the molecular markers or breeding the high meat-quality chickens.