To evaluate the role of ferulic acid esterase (FAE) in the degradation of lignocellulosic agricultural by products, an in vitro cumulative gas production trial was conducted to investigate the effect of 16 h at 39 ℃ FAE pretreatment (2% in air-dried substrate) on subsequent 72 h rumen fermentation characteristics of Chinese wildrye(CW), corn stalk (CS), rice straw (RS) and wheat straw (WS) inoculated by rumen fluids from Holstein steers. The results showed that in vitro dry matter disappearance did not differ between the control groups and FAE groups （P>0.05）. Within the control groups, total volatile fatty acid (TVFA) production occurred: CW>RS>CS>WS. TVFA of WS, CS, CW and RS in FAE treatments were respectively increased by 13.9%, 13.6%, 7.6% and 3.0% compared with the control groups (P<0.05). Meanwhile, the 72 h cumulative gas production (mL/g DM) of CW and WS in FAE treatments were increased by 42.2% and 16.6%, respectively (P<0.05), and the gas production rate (h-1) of WS was increased by 37.5% (P<0.05). In general, roughage pretreated by FAE will be favorable for microorganisms to exert their fibrolytic potentials in the rumen, which would give a reference for further development of feed-use esterase with animal feeding trials.［Chinese Journal of Animal Nutrition, 2010，22（1）:207-211］