Abstract: The bagasse fiber reinforced polypropylene composites were fabricated by injection molding, and the mechanical properties of the composites were investigated in terms of the effects of fiber mass fraction, injection molding conditions and additive. The results indicate that the flexural modulus increases with the increase of fiber mass fraction. All the mechanical properties decrease with the increase of cylinder temperature due to the thermal degradation of the bagasse fibers. Under the conditions of mold temperature 90 ℃, 30 s interval, and different cylinder temperatures 185 ℃ and 165 ℃, the flexural properties and the impact strength show the maximum values, respectively. After the addition of maleic anhydride grafted polypropylene, the flexural strength and the impact strength are improved.