The methane content was 45.9–70.0% and rate of VS reductionwas 55.8%. The biogas yield of 674.4 L/kg VS was higher than that of the digestion of rice straw or pigmanure alone by 71.67% and 10.41%, respectively. Inhibition of biogas production by volatile fatty acids(VFA) occurred when the addition of kitchen waste was greater than 26%. The VFA analysis showed that,in the reactors that successfully produced biogas, the dominant intermediate metabolites were propionate and acetate, while they were lactic acid, acetate, and propionate in the others.