Abstract: The muscle fiber characteristic, MyHCs gene expression, metabolic enzyme activity and meat quality traits in Longissimus dorsi of 6-month-old Sunit sheep were measured by ATPase histochemical staining technique and real-time fluorescence quantitative technique to investigate the effects of dietary lactic acid bacteria on muscle fiber types and meat quality of Sunit sheep. In addition, the relationship between muscle fiber properties, MyHCs gene expression and meat quality were analyzed. The results showed that the proportion of typeⅠmuscle fibers and the genes expression of MyHCⅠ, MyHCⅡa and MyHCⅡx were increased significantly (P<0.05), lactate dehydrogenase activity, muscle pH, L^* and shear force value were significantly decreased (P<0.05), and a^* value was significantly increased in the lactic acid bacteria group (P<0.05). Correlation results showed that the pH₀ of Longissimus dorsi was significantly negatively correlated with MyHCⅡx gene expression (P<0.01), the pH₂₄ was significantly negatively correlated with the proportion and area ratio of typeⅠmuscle fibers (P<0.05). L^* value was significantly negatively correlated with MyHCⅠ gene expression (P<0.05), and a^* value was significantly positively correlated with the number of typeⅠmuscle fibers and MyHCⅡx gene expression (P<0.05). In summary, dietary lactic acid bacteria could improve the muscle color and tenderness by increasing the proportion of oxidized muscle fibers, thereby improving the meat quality of Sunit sheep.