In this study, a novel integrated process combining simultaneous partial nitrification, anammox, and denitrification (SNAD) with anaerobic hydrolysis and acidification (AnHA) was proposed for the treatment of municipal sewage with low carbon-to-nitrogen ratio (C/N). The average removal efficiencies of chemical oxygen demand (COD) and NH4+-N in AnHA were 27.15% and 1.45%, respectively. Meanwhile, the removal rates of COD and total nitrogen in SNAD were approximately 83.12% and 79.13%, respectively. Fluorescence in situ hybridization results showed that acidogenic bacteria accounted for 92.4% of all bacteria in AnHA. The dominant bacterial group in the aerobic layer of the SNAD biofilm was ammonium-oxidizing bacteria (65.13%), whereas that in the anaerobic layer was anammox (47.17%) and denitrifying (38.91%) bacteria. Compared with the energy consumption of the anaerobic-anoxic-oxic process (100%), the AnHA-SNAD energy consumption was only 53.2%, which indicated an energy-saving alternative process for low C/N municipal sewage treatment.