Bilateral sequential cataract surgery is very common in clinical,but the ophthalmologists often ignore how to choose the timing of operation and whether the first eye can be used to improve the intraocular lens (IOL) power calculation for the second one.Despite the refinements in IOL selection with the use of third-generation IOL formulas,5％ of eyes still result in a postoperative refractive surprise of ± 1.00 D or more.This paper introduced the methods of using refraction error of the first eye to improve the IOL power calculation for the second eye,and the refractive error of the second eye can be improved by modifying the IOL power to correct up to 50％ of the error from the first eye in details.Because of the variation of the postoperative refractive surprise within a month,the interval of three to four weeks between two eyes cataract surgery is highly recommended.These conclusions may provide the advantageous guidance for us in the selection of IOL in bilateral cataract surgery.