Fuente: WIPO "circular economy" The invention discloses a recycling method for deeply dewatering municipal sludge and gasifying and pyrolyzing sludge cake by the aid of water vapor to produce hydrogen, and belongs to the field of technologies for dewatering, pyrolyzing and utilizing municipal sludge. The recycling method includes steps of adding composite conditioners into the sludge to condition and improve the dewatering performance of the sludge so as to obtain conditioned sludge and dewatering and treating the conditioned sludge to obtain deeply dewatered sludge cake with the moisture content of 40-65%; further naturally drying and treating the deeply dewatered sludge cake to obtain dried and deeply dewatered sludge cake with the moisture content of 10-60%; carrying out sludge pyrolysis on the dried and deeply dewatered sludge cake in protective gas atmosphere to obtain pyrolysis gas. The composite conditioners comprise oxidizing reagents and red mud. The recycling method has the advantages that pyrolysis processes are low in comprehensive energy consumption, the yield of the pyrolysis gas can be increased, and the quality of the pyrolysis gas can be improved.