The micromolar calcium activated neutral protease (CAPN1) and calpastatin (CAST) have been widely regarded as genes related to muscle growth and meat tenderness. The objective of this study was to verify the association of SNPs of CAPN1 and CAST genes with carcass and tenderness traits and search the possible change patterns of SNPs in CAPN1 and CAST genes in six generations of broiler breeding process for growth rate, efficiency, and reproduction, during the third generation and the ninth generation, respectively. We found that, for CAPN1, genetic effects between SNPs (G3535A, C7198A) and meat tenderness were similar in different generations, while SNP3 (G7324A) was a novel polymorphism and had significant association with carcass and tenderness traits (P < 0.05) in this study. Furthermore, there was significant association between SNP4 (G9950A) and carcass indexes instead of tenderness traits (P < 0.05) which was consistent in the two generations. Moreover, although SNP6 (G37868A) of CAST had no relevance to carcass traits or tenderness traits in the third generation, it showed significant association with LW and CW in the ninth generation (P < 0.05).