A die-quenching process is one of the hot forming processes for making sturdy automobile parts. The process has some problems; low productivity, variation of temperature of dies and strength of materials, and all that. These problems are disordered for extending and upgrading the die-quenching process. The solution of this problem is figured out the characteristics of the die-quenching process. For the experiments, water-cooling dies were made from stainless steel and an installed chamber of a high-precision compress testing machine. In the experiment, temperature of dies and a workpiece was measured. Then, martensitic transformation time of the workpiece and maximum temperature of the die were obtained from these data for evaluation of quenching. After the experiment, hardness and microstructure of high-strength steel were obtained from an observation of the quenched workpiece. From these results, a new valuation method on the effect of die-quenching parameters is proposed and relationship among forming time, cooling rate of workpiece and temperature of dies was verified in this investigation.