Abstract: The composites of kenaf (KF) reinforced polypropylene(PP) and palm(PF) reinforced polypropylene(PP) were modified by PVA crosslinking. PF/PP and KF/PP composites were prepared by compression molding process.The effects of different crosslinking methods on the structure and properties of composites were studied.SEM and DMA were used to describe the interfacial bonding and mechanical properties of the composites.The results reveal that the PVA and coupling agent have the best effect on the natural fiber reinforce PP composite.When the KF/PP is modified by 5%PVA and 3% coupling agent, the flexural strength increases by 25.2%, the flexural modulus increases by 35.49%, and the shear strength increases by 28%, which reach 50.90 MPa, 5.76 GPa, 5.4 MPa, respectively.When the PF/PP is modified by 5%PVA and 2% coupling agent, the flexural strength increases by 31.46%, the flexural modulus increases by 27.07%, and the shear strength increases by 21.75%, which reach 44.33 MPa, 2.32 GPa, 5.18 MPa, respectively.The water content of the modified KF/PP and PF/PP composites are reduced by 46.89% and 10.63%, respectively, the water absorption of the modified KF/PP and PF/PP composites are reduced by 8.57% and 6.12%, respectively. After the modification of KF/PP, the storage modulus increases by 20.93%.The T_g value of the modified PF/PP composite increase from 90.1℃ to 113.8℃, which increases by 26.30%. SEM reveal that the crosslinking modification of PVA and coupling agent effectively improve the adhesion between fiber and polypropylene, and the interface bonding between the fiber and polypropylene is also improved.