The magnesium oxysulfate whiskers/PE composites were prepared by melt-extrusion using whiskers as filler. The mechanical performances, including the tensile strength, elongation at break and elastic modulus, were tested by electronic universal testing machine. The results show that as the content of whiskers increases, the modulus of elasticity increases while the elongation decreases. However, the elastic modulus will improve and the tensile strength will be maximized when it is 15%. Hydrogen bond was formed between whisker and modifier after modification and was characterized by IR. The morphology of fracture was analyzed by SEM. It draws the conclusion that hydrogen bond is capable to enhance the mechanical performances of composites.