PCR-RFLP technique was applied in this study to analyze the distribution of MyoD genotypes in 10 different pig breeds and pig breed crosses. The genetic effects of MyoD gene on muscle fiber, carcass quality, carcass grading traits and meat quality traits were analyzed. The results indicated that the MyoD/DdeⅠ polymorphisms detected in the intron 1 of the gene were abundant in these testing pig breed groups. The C allele was more frequent in most Chinese native pig breeds and mainly existed in the form of AC heterozygotes. The mutation allele A had significant positive effects on most of carcass quality traits and carcass grading traits, but had negative effects on most of meat quality traits. The A allele can highly significantly increase the carcass lean percent, loin eye area, ham percent and carcass length, and decrease fat content (P<0.01). The A allele had additive effects of increasing 457.915 μm2 of the size of muscle fiber, 3.594% of the carcass lean percent, 3.084 cm2 of the loin eye area, -3.915 5% of the carcass fat content, 0.771% of the ham percent, -0.145 and -0.160 of the meat color score tested by color plate at 45 minutes and 24 hours after slaughtered. The A allele had dominant effects of increasing 431.055 μm2 of the size of muscle fiber, -0.153% of the carcass lean percent, -0.46 cm2 of loin eye area, 0.666% of the carcass fat content, 0.068% of the ham percent, -0.052 and -0.213 of the meat color score tested by color plate at 45 minutes and 24 hours after slaughter respectively.