A PLA-based bagasse cellulose composite material with excellent performance and low cost was prepared. As one of the most commonly used thermoplastic materials in fused deposition modeling (FDM), PLA is currently the most widely used three-dimensional (3D) printing technology. It has the natural advantage of being biodegradable. However, due to its poor toughness, it cannot meet the requirements for 3D printing consumables in some areas. Therefore, polylactic acid (PLA) is used as the matrix, tert-butyl peroxybenzoate (TBPB) are used as the free radical initiator, and glycidyl methacrylate (GMA) is used as the reaction monomer to prepare the PLAGMA graft product, which realizes the toughening of PLA, and the PLA/PLA-GMA/BC (bagasse cellulose) composite material is prepared by the physical blending method, which realizes the reinforcement of PLA; it was proved by fourier transform infrared spectroscopy (FTIR) and 1H NMR that GMA was successfully grafted onto the PLA molecular chain, and the influence of the grafting rate on the toughness of PLA-GMA was explored. It was concluded that the grafting rate of PLA-GMA with the best toughness was 10.33\%. The strength is 15.94 MPa, the modulus of elasticity is 969.01 MPa, and the elongation at break is 278.17\%, which is about 44 times the elongation at break of pure PLA. The PLA/PLA-GMA/BC composite material with high cellulose loading was prepared by physical blending. The effect of PLA-GMA content, BC particle size and BC content on the properties of composite materials was explored. The results showed that PLA-GMA when the addition amount is 25\%, the capacity enhancement effect is the best; when the additional amount of BC is as high as 40\%, the PLA/PLA-GMA/ BC composite still has good mechanical properties, and the addition of BC can promote the crystallization of PLA; DSC results show that BC can promote the crystallization of PLA, and the addition of PLA-GMA is not conducive to the composite material the formation of PLA crystalline regions; the temperature at the maximum decomposition rate of 40\% BCB/25\% PLA-GMA/PLA composite material is 355.44 celcius, and the thermal stability is improved. This study proves that the functional group properties of GMA realize the toughening and enhanced dual modification of polylactic acid, which expands the choice and application range of FDM 3D printing materials.