Abstract: The influence of white-rot fungi pretreatment of corncob on vapor-hydrolysis with propionic acid to make cellulose was studied. The results showed that manganese peroxidase(MnP), lignin peroxidase(LiP), laccase, xylanase and cellulase treatments reached their biggest enzyme activities during the bio-treatment processing of corncob after 5, 6, 7, 15 and 10 d respectively, which were 1.326, 10.25, 0.0627, 0.33 and 403 U/g, respectively. The optimized conditions of vapor-hydrolysis with propionic acid on corncob using response surface methodology were as follows: ratio of solid to liquid 1:10(g:mL), 70 min, concentration of propionic acid 900 g/L, the content of cellulose reached 91.09% of the product. After bio-treatment for 10 d, content and retention rate of cellulose were 97.12% and 94.70%, respectively, while contents of hemicellulose and lignin were 0.96% and 0.92%, respectively.