Aerobic granular sludge-based simultaneous nitrification, denitrification and phosphorus removal (SNDPR) systems were configured for the treatment of low-strength municipal wastewater. Granular characteristics, process performance, and the corresponding microbial ecology dynamics were comprehensively explored with sodium acetate and succinate as mixed carbon source. Results revealed that aerobic granules kept structural and functional resilience, while mixed carbon source largely altered and balanced the growth and competition of phosphorus/glycogen accumulating organisms (PAOs/GAOs). Appropriate ratio of mixed carbon source was vital for superb physiochemical behaviors and reliable removal performance by aerobic granules. Therefore, the aerobic granular SNDPR system could achieve deep-level nutrients removal through enhancing the anaerobic carbon uptake rate and strengthening the carbon usage efficiency. The present work could add some guiding sight into the application of aerobic granular SNDPR system for wastewater treatment.