Abstract <p>Poor stability is one of the main drawbacks for aerobic granular sludge (AGS) in application, especially under low hydraulic shear force. In this study, a novel magnetic modified low expansion vermiculite (MLEV) was prepared and applied to establish AGS system (R3) under 0.8 cm/s superficial gas velocity. For comparison, two parallel reactors with traditional cultivation way (R1) and unmodified low expansion vermiculite (LEV) addition (R2) were also operated at the same conditions. Results showed that LEV had little effect on the granulation process, granules in R1 and R2 undergo large-scale disintegration from day 48. However, the addition of MLEV not only shortened the granulation time by 30% but also increased the mechanical strength of granules by two times. Characteristic analysis indicated that magnetic modification increased the material specific surface area (3.19-fold than LEV) and changed the surface charge from negative (LEV: -22.47±1.23mV) to positive (MLEV: 27.5±0.9mV), and induced a micromagnetic field in LEV, which stimulated the secretion of extracellular polymeric substance, and promoted the enrichment of functional microorganisms. At the end of the experiment, only the TN removal rate of R3 exceeded 70%, while the rates of the other two reactors were all below 60%. Overall, MLEV could act as nucleating agent to accelerate floc coaggregation and improve granule stability under low shear force. Notably, the addition of MLEV effectively suppressed over proliferation of the filamentous bacterial genus <i>norank_f_Actinomycetaceae</i>, maintaining its relative abundance at approximately 50% of levels observed in both control groups, thereby preventing granule disintegration induced by the filamentous bulking. This approach offers a viable strategy to accelerate AGS formation and enhance stability under low superficial gas velocity conditions.</p>