The author studied as follows: (1) The influences of Cr, Ni, W, Mo, V, Ti, Cu of the high Mn-Cr steels on the high temperature (up to 800°C) mechanical properties of the high Mn-Gr steels, at the same time, for reference, on some of decrease of toughness when kept at about 700°C after quenched from 1050°C and on the scaling. (2) The effect of Ti of the high Mn-Cr-W-Mo steels on the decrease of toughness, not only at the room temperature, but also at the high temperature up to 700°C, when kept for long time at 750°C after quenched from 1050° and 1200°C.(3) The influences of C and V of the high Mn-Cr steels on the hardness and the shock value when quenched from 1000-1200°C and tempered at 500-800°C. (4) The influences of the conditions of every heat-treating process of the high Mn-Cr-V steels. (5) Additional remarks; The influences of V and Ti of 14% Cr-14% Ni-W steels on the shock value and the hardness when heated at 1000-1350°C and when kept for long time at 750°C after quenched from 1100 and 1200°C.