In this work, LiBH4-20 wt％ PP composite was prepared by ball-milling with as-synthesized hierarchical pyr-olysis polyaniline (PP) and LiBH4, and the hydrogen sorption performance as well as catalytic mechanism of the composite was studied. It is found that the onset desorption temperature of the composite decreases to 75 ℃, almost 235 ℃ lower than that of the milled LiBH4. Moreover, the composite could release 4.1 wt％ H2 and rehydrogenate a total of 4.4 wt％ H2 when the temperature raiseds up to 400 ℃, showing an outstanding re-versibility, which even 3.9 wt％ H2 can be kept after five cycles. Through scanning electron microscopy (SEM) observation and X-ray diffraction (XRD) analysis, we found that the PP surface forms some nanoholes after hydrogenation-dehydrogenation cycles, which leads to the confinement of some LiBH4 in the PP nanoporous structure, therefore, the hydrogen sorption kinetics and reversibility are significantly enhanced. In addition, we also found the oxygenic groups of the PP can react with LiBH4 forming LiBO2 and Li3BO3, where the containing Li-B-O bonds loaded in the porous structure of the PP catalyze the hydrogenation reaction of LiBH4.