Abstract: In order to obtain a higher biogas production capacity through co-degradation of corn straw and lignite, the influence produced by each of the following four factors is investigated—temperature, pH value, lignite particle size and straw-lignite ratio. The orthogonal test is then made based on the appropriate factor levels selected according to single factor test result. Test result shows that each of the abovegoing factors can exert a noticeable effect on the biogas production rate; as evidenced by orthogonal test, an optimal gas production condition can be achieved at an culture temperature of 40 ℃, a pH value of 7.5, a lignite particle size range of 0.45~0.90 mm and a straw/lignite ratio of 1.5 ∶1; under such conditions, the net methane production rate in 60 days can reach 63.39 mL/g; and the straw/lignite ratio is the most influential factor among the others.