In order to improve producing gas efficiency by anaerobic fermentation of the dairy manure, solid-liquid separated pretreatment of dairy manure and anaerobic co-disestion of separation liquid and pig manure were investigated. The results indicated that separation liquid separated pretreatment of dairy manure reduced the material viscosity and favored mass transfer of microorganism. In the comparative fermentation trial of dairy manure separation solution and dilute dairy manure, gas production of separated liquid was increased by 32.68% than that of diluted dairy manure and methane yield was improved by a large margin. In a proper mixture proportion of dairy manure and pig manure, a good fermentation result would be achieved. In the experiment, the process of biogas producing was stable and the cycle was relatively short at 10.49%mixture group. Furthermore, the biggest cumulative biogas production was 59.8 L. It increased by 26.24% compared with pig group (TS is 8.00%) and 43.51% compared with mixture group (TS is 8.54%). The results showed that biogas yield was increased significantly under the condition of mixture composited of dairy manure and pig manure (TS is 10.49%). 