AIM:To calculate and compare the degrees of surgery induced astigmatism (SIA) in phacoemulsification and intraocular lens (IOL) implantation with 3.2mm clear corneal incision in different positions and to analyze the effect of incision on corneal curvature. METHODS:Eighty-eight cases 100 eyes were randomly divided into two groups:group A with incision at temporal (9∶00 or 3∶00) clear corneal,group B with incision at superior (12∶00) clear corneal. All patients underwent phacoemul-sification and foldable acrylic IOL implantation. Corneal curvature radius was obtained at preoperative and postoperative 3 months. The SIA degrees were analyzed by Jaffe/Clayman vector method. We compared SIA degrees between groups,corneal curvature at incision meridian and at another meridian between preoperative and postoperative. RESULTS:The mean SIA degrees between two groups showed no significant difference (P=0.483). There was significant difference(P=0.006) between preoperative and postoperative corneal curvature at incision meridian. There was no significant difference(P=0.084) between preoperative and postoperative corneal curvature at another meridian.CONCLUSION:SIA degree in phacoemulsification with 3.2mm clear corneal incision has no connection with incision positions. Corneal curvature at incision meridian will be released,but another meridian has no distinct effect. The SIA analyzed by Jaffe/Clayman vector method will provide an important reference for toric IOL implantation surgery.