Objective By discussing the accuracy of A-scan and IOL Master in intraocular lens power measurement, to offer Objective clinical data for cataract surgery.Methods Three hundred patients(300 eyes)with age-related cataract were included in the study. Before surgery,axial length was measured by A-scan and IOL Master respectively and corneal curvature was measured by auto refractometer. A-scan group used the corneal curvature data of the auto refractometer. IOL Master group used the corneal curvature data from the instrument. Intraocular lens power was calculated according to the SRK-T formula.We observed the refractive state of 3m after operation, detected and analyzed the patient's refractive data by the auto refractometer.Results All patients who were included in the study were randomly divided into A-scan group and IOL Master group.The mean axial length was (23.21±0.59) mm measured by A-scan, the mean axial length was (23.22±0.59) mm measured by IOL Master. There was no significant difference between them (P>0.05). The preoperative mean corneal curvature measured by the auto refractometer was (44.01±1.79)D. The preoperative mean corneal curvature measured by IOL Master was (44.13±1.62)D. There was no statistically significant difference between them (P＞0.05). The mean absolute refractive error ( MAE) in A－scan group was (0.43±0.26)D and in IOL Master group was (0.42±0.17)D. There was no statistically significant difference between them (P＞0. 05).Conclusion IOL Master group operated slightly better than A-scan group, but we did not find a significant advantage in intraocular lens power measurement with A-scan group. IOL Master may not completely replace A-scan. The combination of the two ensures the accuracy of the measurement in intraocular lens power.