Abstract: By the test on the operation of a 300m³ mesophilic temperature—digestion plant, the paper represents and analysis the relationship between biogas production yield from cows manure and dry mass concentration, BPY with operation temperature in tank, net energy production with energy consumption reouirement under condition of mesopphilic operation.According to nalyses on the test, we gain factors effecting net tnergy production which include insulation performance of a digester operating emperature, ambient temperature. Meanwhile evaluate the rationality of the plant.