Abstract: The rice straw fiber and acrylonitrile-butadiene-styrene(ABS)were used for the raw materials. The acticarbon, Al₂O₃、SiO₂ and silane coupling agent were used for modifiers, respectively. The modifier-straw fiber/ABS composites were prepared via mixing molding process. The reinforcing effect and its strengthening mechanism of several different modifiers were compared. The results show that the effect of silane coupling agent on the straw fiber/ABS composites is poor, and the strengthening of the acticarbon, Al₂O₃ and SiO₂ on the composite is better than silane coupling agents, in which the enhancement effect of Al₂O₃ is the best. When the mass ratio(Al₂O₃:ABS) of Al₂O₃ is 5%, the tensile, flexural and impact strength reach the maximum values which is 27.719 MPa, 61.05 MPa and 26.53 kJ/m²; when the amount of inorganic addition is 5%(inorganic:ABS), the water resistance of composite adheres to:5% Al₂O₃ >5% acticarbon > 5% SiO₂ > not added, which is in accordance with the gra-dient of mechanical properties of the modifier-straw fiber/ABS composites, the rheological properties of composite adhere to:5% acticarbon > 5% Al₂O₃ > 5% SiO₂ > not added.