Using the steam exploded pretreatment technology to process the corn stalk, and then the pretreated corn stalk were used the materials of anaerobic fermentation under the temperature 35°C. Experimental results show that: the biogas production per unit of pretreated corn stalk increased 16.8 % ~ 63.2% than the unexploded corn stalk. The gas production can up to the peak (484.3ml / g dry steam exploded straw) under the condition (retained time 90s, pressure 3.0Mpa). The longer the retained time is the earlier the gas production peak occurs under the same steam pressure and the peak range become wider. The main gas production area is the former 20d, the production amount to about 80% of total production, while the gas production of untreated straw fermentation in is only 60% of total production under medium temperature.