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In this paper, a porous silicon powder material and a porous silicon/graphene composite material were prepared by using Al-20Si alloy as a raw material, and used as a negative electrode material for lithium ion batteries. A porous silicon powder material was prepared by etching an alloy with hydrochloric acid. Porous silicon/graphene composites were prepared by ultrasonically adding different amounts of graphene (0, 5%, 10%, 15%, 20%, 25%) to a silicon-based material, respectively. The experimental results show that the addition of 10% graphene to the porous silicon-based material had the best electrochemical performance. The first charge and discharge capacity was 2 552 mAh/g, and the charge and discharge capacity was finally stabilized at 540 mAh/g. The first charge and discharge efficiency was 78.5%. After the five cycles, the efficiency during subsequent charging and discharging was maintained at about 98%. When the amount of added graphene exceeded 10%, the performance gradually decreased as the amount of addition increased. The addition of graphene reduced the charge-discharge specific capacity but increased the cycling stability of the silicon. [ABSTRACT FROM AUTHOR]