During the initial stage of aerobic granulation (10~16d), the aluminum sulfate feeding strategy was applied to accelerate the granulation of aerobic granules. The elements content were analyzed by X-ray fluorescence spectrometer (XRF). Scanning electron microscope combined with energy dispersive X-ray detector (SEM-EDX) were used to analyzed the spatial distribution of elements. The results showed that the granules cultivated with aluminum sulfate had more compact structure, more biomass and better characteristics. After chemical dosing, the content of aluminum in granules linearly decreased from (45.69±0.55)% (16d) to (1.09±0.39)% (43d). Meanwhile, the content of P and S recovered from (7.21±0.047)% and (32.11±0.23)% to (13.64±0.071)% and (47.82±0.21)%, respectively. Aluminum mainly accumulated in the core of the mature granules and was in the form of precipitate. During the chemical dosing, the aggregation of microorganism was mainly caused by the physical flocculation. Since the chemical dosing terminated, the self-flocculating of microorganism gradually replaced the inorganic flocculation of flocculant and became the main mode for microbial aggregation. The results prove that Al³⁺ accelerated granulation is a coupling process between physicochemical-biochemical effects.