Gear skiving has obvious advantages of efficiency and precision in the pre-grinding process of cycloidal gear. The precision of skiving is mainly affected by the actual errors in processing system. In order to investigate the influence of error factors on skiving precision, the mathematical model of the sweeping trajectory of cutting edge was established based on the motion model of gear skiving. The shape of the edge-sweep surface was analyzed related to each error factor. The maximum deviation between the actual edge-sweep surface and the theoretical tooth surface was calculated by discrete comparison method, and the machining error could be predicted theoretically. Finally, the control variable method is used to set up the test cutting experiment. Measuring the actual workpiece size and analyzing the influence of each error on the tooth profile error. The results show that the center distance error, the coaxiality error of clamping and the cutter manufacturing error have specific influence on the tooth profile error of the workpiece. The center distance error is reflected in the tooth profile error by a proportion of 1:1 approximatively. The coaxiality error of cutter clamping is reflected in the tooth profile error by a proportion of 1:2 approximatively. The manufacturing error of cutting edge is reflected in the tooth profile error error by a proportion of 2:1 approximatively. The above research provides a theoretical basis for tolerance setting and adjustment of error factors.