In order to determine the interaction rule of fat, starch and protein in the process of anaerobic fermentation, the influence of different mixing ratios on the characteristics of methanogenesis and degradation was investigated using mixture design under mesophilic condition. The results revealed that when fat, starch, and protein was used as substrate separately, the methanogenesis performances were inhibited in different degrees, and the mean biochemical methane potentials (BMP) were 345.36, 59.80 and 135.87mL/g, respectively, which accordingly accounted for 34%, 14% and 26% of theoretical methane production. At the same time, the degradation property was affected apparently. However, the synergistic effects on methanogenesis and degradation were obvious while the three components were mixed as substrates. The regression models between the organic ingredients mixing ratios and BMP and volatile solid (VS) degradation rate were established, furthermore, the parameter optimization was carried out. The optimization result was that as the ratio of fat, starch and protein was 36∶30∶33, BMP and VS degradation rate were maximum. Experimental verification showed that BMP and VS degradation rate were 451.36mL/g and 79.62% respectively at optimal ratio.