In the context of carbon neutrality, it is of good economic and ecological value to replace synthetic fibres with natural fibres as reinforcing materials in the preparation of composites. The effect of the hot pressing process parameters on the physical and mechanical properties of the LBF/PP composites was further investigated. The distribution of LBF in the composites was observed by CT. The experimental results show that the hemicellulose content of the BF decreases and the lignin content decreases after the alkali treatment. The mechanical properties of the LBF/PP composites were better at a hot pressing temperature of 180°C, a hot pressing pressure of 8 MPa, a hot pressing time of 15 min and a mass fraction of 70% LBF, with bending strength and bending modulus reaching 226.1 MPa and 15.1 GPa respectively. CT results show that the fibres are evenly distributed in the composites and that the hot pressing process allows the molten PP to penetrate the pores of the LBF surface, forming a good physical and mechanical bond. These composites can be used in various applications such as construction, automotive, consumer goods etc. They are considered to be a suitable alternative to solid plastic products and materials.