The fermentation mycelium of Paecilomyces militaris was added to the diet of broiler to study the effects on the carcass performance and the muscle quality of broilers(The addition rate was 0.25% and 0.5%.).The results showed that dietary supplementation of fermentation mycelium of Paecilomyces militaris could increase the live body weight and the content of total amino acids and delicious amino acid of muscle.Furthermore,the results also indicated that the addition of mycelium increased the fat content of breast muscle of broiler significantly(P<0.05)and decreased the muscle dehydration rate dramatically(P<0.05),but it did not affect the carcass performance.In a word,the fermentation mycelium of Paecilomyces militaris could improve the muscle quality of broilers.