With the improvement of cataract operation, the cataract surgery has become increasingly perfect. The cataract patients show greater expectation for the result of cataract operation. As a result, refractive cataract surgery has become the main trend. Detailed investigations of corneal diseases, lens density, corneal topography, preferable intraocular lens(IOL)choice, and IOL power calculation can help us get a better knowledge of preoperative conditions on patients, which can be conducted with pentacam. So we can have a better forecast of post-operative outcome and improve the quality of vision for cataract patients after surgery.