A method of expanding the dynamic range of a Hartmann-Shack (H-S) sensor for measuring the eye′s aberration is proposed.It is a combination of unwrapping algorithm and mask technique,which greatly increases the dynamic range of H-S system. The experimental data shows that it performs well even in the case where the unwrapping method is limited.It also shows that the measurable maximum curvature can be greatly improved compared with the mask technique.When a spherical wavefront incidents,the measurable minimum curvature radius can be reduced from 75 mm to 10 mm by this method,compared with the the mask technique.Actually since it overcomes the limitation of unwrapping algorithm,much higher local curvature can still be measured.