Abstract: In this study, the indexes associated with feed nutritive value ofJuncao spent mushroom （Pleurotus eryngii） substrate, including routine nutrients content, Ca, P and other mineral elements content, amino acid content, heavy metal content, and aflatoxin content were determined. The results showed that the Juncao spent mushroom （Pleurotus eryngii） substrate was rich in nutrition which had abundant crude protein, crude fat, amino acids, mineral elements and other nutritional components. Its nutritional value was similar to that of sugar-beet pulp and was superior to that of Leymus chinensis and rice straw. Its heavy metal content and aflatoxin content meet the requirement of the national standard for hygienic quality of feed. It is indicated that the Juncao spent mushroom （Pleurotus eryngii） substrate has comparable nutritional value to the commonly used roughage and is able to replace them in diets of herbivorous animals.