Cornea is the most important optical surface in the eye dioptric system. Three kinds of methods in measuring corneal astigmatism were used. Three hundred and sixty eyes suffered ametropia were selected on a random basis. Computer-assisted corneal topographic system was compared with keratometer and cycloplegic,retinoscopy in measuring corneal curvature. There was no statistical difference in axes of astigmatism among the three groups. It is thought that Delta K-sim could show the corneal regular astigmatism. As for diopters of astitigmatism, no difference was found between the groups of corneal topography and keratometer, but there was a significant difference between the group of cycloplegic retinoscopy and the other two groups. It was demonstrated that keratometer could function similarly as the corneal topography. However, it measured only four points from a small region of the cornea and was limited in measuring slight changes in corneal curvature. Some discussion was also made about the graphic patterns and Delta K-sim in corneal topography.