High hardness steel generally means its hardness over HRC45. This using CBN tools for turning. Tool breakage and damage during turning process cause material loss and additional tool cost. If it is predicted during the process and accumulate this data as a turning parameter it will be of help to turning mechanism understanding. For this purpose neural technology give beneficial as prediction, categorization, searching and enable nolinear function for pre-diagnosis algorithm. In this study we appraise the accuracy of prediction by applying backpropagation neural networks (BPNs) method in the high hardness steel turning.