Abstract: Poly(vinyl chloride) (PVC)/wheat straw composites were prepared by a compression molding method, and effects of contents of wheat straw powders and different coupling agents on their mechanical properties and contact angle were investigated The results indicated that the composites achieved a maximum flexural strength when 40 wt % of straw powders was incorporated, and the straw powders were homogenously dispersed in the PVC matrix, leading to good properties of the composites The mechanical properties of the composites could be further improved through the modification of straw powders with coupling agents, and their flexural strength and Rockwell hardness achieved the optimum values with addition of 50 wt % straw powders In this case, the straw powders could be distributed in the matrix more homogenously due to the surface modification with coupling agents