Abstract: The effect of solid phase stretching on the microscopic crystalline structure and macroscopic physical properties of iPP sheet containing β-nucleating agent was investigated. The crystallization behavior of iPP sheet after solid phase stretching was studied by X-ray powder diffraction. The microstructure of iPP sheet was studied by scanning electron microscopy and polarized light microscopy. The physical properties of iPP sheet were evaluated by means of universal tensile testing machine, pendulum impact tester and softening point tester. The results indicated that the iPP sheet achieved the optimum mechanical properties at 130 ℃. The impact strength of iPP sheet was almost double of the value for the unstretched iPP one but its tensile strength showed an unchanged value.