Abstract: The interface compatibility between plant fibres and plastics is poor because the former is polar and hydrophilic, while the latter is nonpolar and hydrophobic. So, WPCs(wood plastic composites), with PE as matrix, natural rice straw and acetylated rice straw as fillers, were prepared by blending and extrusion. The impact of blending conditions on the microstructure and tensile properties was studied. The results showed that the tensile properties of natural rice straw/PE composite were poor due to a large number of bubbles existed within the structure, which resulted in stress defects. After acetylation, the interface compatibility between rice straw and PE was improved remarkably because the polarity and hydrophilism of rice straw fibres were reduced. When the mass fractions of rice straw were the same in WPC, the tensile strength and the elongation at break of acetylated rice straw/PE composites were 1.5 and 2 times those of natural rice straw/PE composites, respectively.