The effect Pleurotus ostreatus inoculation on nutrient value of corn stalks was studied in non-sterile conditions.Non-sterile corn stalks were inoculated with P.ostreatus under the conditions of storage treatment at 18℃.Sampling was taken after 20 d,23 d,26 d,29 d,32 d,35 d and 38 d.The results showed that after P.ostreatus inoculation treatment,crude protein increased by 41.7%-63.9%.The highest crude protein content of 6.21% was gotten in 32 d.Content of CF decreased significantly compared with untreated group,and the lowest CF content was gotten in 38d,which was 40.1%.