The granular stability, nutrients removal and phosphorus (P) accumulation of algal-bacterial aerobic granular sludge (AGS) was examined by using shaking photoreactors (at a fixed light/dark cycle of 12 h/12 h). During the 25 day's operation, algal-bacterial AGS possessed good granular integrity (8.4 +/- 0.6%), and excellent removals of dissolved organic carbon (94.8 +/- 1.6%) and total nitrogen (71.1 +/- 3.3%). More extracellular proteins (153.7 +/- 2.3 mg/g) were excreted from the granules with a high proteins/polysaccharides ratio (similar to 7.4) on day 25, especially the tightly bound proteins mainly responsible for granular stability. Decrease in P content, especially non-apatite inorganic P relating to Fe-PO4 precipitates, was detected in the granules to some extent, although 54.8 +/- 17.1% of total P removal was achieved during the light-on cycles. Still, high P bioavailability (92.0%) was kept in the algal-bacterial AGS throughout the test period. Further optimization of light-on/light-off cycle and hydraulic/sludge retention time is demanding for better and stable P accumulation in the algal-bacterial granules with high bioavailability.