Abstract: Environmentally-friendly air filtration composite materials were prepared to filter polluted air using soybean protein and bacterial cellulose (BC) as raw materials. 7S and 11S with high solubility were firstly obtained through purification and separation of soy protein by adopting Nagano. Thereafter, soy protein isolate (SPI), 7S and 11S were treated with acrylic acid to unfold the polypeptide chains. Finally, modified soy protein-BC (MSPI-BC, M7S-BC and M11S-BC) composites were prepared by adding soy protein treated with acrylic acid to BC. Besides, the morphology, air filtration efficiency, adsorption capacity and air penetration of the modified soy protein-BC composites were evaluated. The results show that MSPI unevenly distributes in BC, aggregating on the surface of BC fibers. While M7S and M11S uniformly cover on the surface of BC fibers, without aggregation. The air filtration efficiency of MSPI-BC, M7S-BC and M11S-BC composites for particulate pollutants is 73.07%±0.02%, 82.13%±0.01% and 85.44%±0.02%, respectively. Moreover, M7S-BC and M11S-BC composites adsorb more particulate pollutants than MSPI-BC composite. The prepared modified soy protein-BC composites in this study own stable structure and high air filtration efficiency, and they are environmentally-friendly, thus being potential to be used in the field of air filtration.