Worm type wheel gear honing machine has been developed for many years. Makers and users often emphasize their polishing effect, deburring ability and noise reducing capabilities. The author accumulates many experiences about carburized gear distortion, does a large amount of experiments and has come to the conclusion that such gear honing, especially the single flank honing has relatively high ability for modifying gear distortion after heatment. This article gives a discussion concerning the duty of honing for hardened gears, the mechanical theory compared with shaving and the data obtained from the experiments and also presents new concept on the scope of application and the new idea about its development.Honing belongs to a kind of superfinishing process, and all such processes have a very similar properties. But gear honing has a very different characteristic and various method of honing, the complex form of the tool making it much different from other superfinishing processes. How and to what degree this honing can do for the improvement is the aim of this article.