NOVELTY - Producing hydrogen and methane at high efficiency by mixing and fermenting municipal sludge and garbage comprises: (a) preparation of generating sludge; (b) alkaline hydrolysis; (c) generating hydrogen; and (d) generating methane.    USE - The method is useful for producing hydrogen and methane at high efficiency by mixing and fermenting municipal sludge and garbage (claimed).    ADVANTAGE - This method can obtain high heating value and clean hydrogen and methane to attain to the resource utilization of the wastes, as well as solve the pollution of municipal sludge and garbage to the environment. Each of the reactors can operate in batches as well as in sequence; the device needed is simple, the operation is convenient and the cost is low.    DETAILED DESCRIPTION - Producing hydrogen and methane at high efficiency by mixing and fermenting municipal sludge and garbage comprises: (a) preparation of generating sludge: taking the anaerobic activated sludge from the sewage plant as the methane generating sludge, and the thermally treated and activated anaerobic activated sludge from the sewage plant as the hydrogen generating sludge, namely air drying the anaerobic activated sludge, then grinding and screening; heating the activated sludge for 2 hours at the temperature of 105 degrees C to kill those which are not spore formers and produce methane bacteria; adding the anaerobic activated sludge to 3 hours/L of glucose nutritional solution after the heat treatment, and adjusting the pH value of the solution to 6.5; subsequently activating for 24 hours at 35 degrees C to produce the hydrogen generating sludge; (b) alkaline hydrolysis: crushing and screening the garbage which has been removed of the non-degradable organic matters; then taking the lime for crushing and screening, and taking the primarily precipitated sludge, residual sludge, concentrated sludge or dehydrated sludge from the sewage plant; feeding the sludge, garbage and lime to an alkaline hydrolysis reactor and mixing them to maintain the carbon-nitrogen ratio (C/N) of the mixture to be 10-30, the lime-organic matters ratio to be 0.05-0.2, and the water content to be 85-99%; and controlling the alkaline hydrolysis time to be 0.5-3 days; (c) generating hydrogen: pumping the mixture after the alkaline hydrolysis to a hydrogen generating reactor; adding the hydrogen generating sludge based on that the volume ratio of the generating sludge to the primer is 0.1-0.5; stirring and mixing them; starting the hydrogen generating reactor for 2-8 days of reaction at 30-60 degrees C; and (d) generating methane: pumping the rest of the mixture after the generation of hydrogen to a methane generating reactor; adding the methane generating sludge based on that the volume ratio of the generating sludge to the primer is 0.1-0.5; stirring and mixing them; starting the methane generating reactor for 7-15 days of reaction at the temperature of 30-60 degrees C.