From the viewpoint of weight saving, it has recently been required to develop high-strength and high-toughness spring steel. Thermo-mechanical treatment (T.M.T.) process would be one of the effective methods to achtieve high mechanical properties of spring steel. Although several studies have been making in this field, it was difficult to obtain the advantage of T.M.T. process, because of the difficulty to control the combination of heating, cooling and forming process effectively. A new compact type T.M.T. simulator based on cotinuous multi-step compression, was developed to study the mechanism of the T.M.T. process. It will be possible for this simulator to apply some different T.M.T. processes such as work-quenching and warm temper forging etc. This paper is mainly concerned with the outline of this simulator and some experimental results of T.T.A. ,T.T.T. diagrams and ausforming. By using this simulator, the process to improve mechanical properties of spring steel would be obtained.