Ａ laboratory scale of multi layer bed fermentation reactor was designed to study the influences of the layering and thickness on biogas characteristic of dry anaerobic fermentation using pig manure as fermentation substrates and straw as regulate material under the leachate recirculation conditions. The results showed that the bed layer anaerobic fermentation had significant impacts on cumulative gas production, the highest Nissan’s volume, and methane content in the gas characteristics of raw materials. When the thickness of bed layer changed from 250 mm to 150 mm, the cumulative gas production rate increased from 135.7 L/kg to 172.1 L/kg, increased by 26.8%. The highest Nissan’s volume increased from 97.4 L to 111.9 L, arose 14.9%, but had no obvious influences in average daily gas production. The highest methane content could be increased by 9% and the time of highest methane content had been advanced with the decreasing of thickness of bed layer significantly. Stratification of fermentation bed had a significant effect on leachate pH and COD value. With the increases of bed thickness, the pH value of three different groups of thickness treatment, 250, 200 and 150 mm, increased by 8.6%, 6.5% and 4.8% respectively from the initial value and the COD dropped by 21.0%, 15.0% and 14.0%. The thickness of bed layer affected leachate infiltration and backflow effect significantly.