Coolingability of coolants is important factor in cooling processor heat treatment of steel, Using standard apparatus and method defined in the Korean Industrial Standard three different shapes of probe were designed, ie, cylinderical, spherical and square on shape with same volume of standard probe. Distilled water and sodium aquious solutions with different concentration of NaOH, NaCl and Na₂CO₃were examined. Estimation of coolingability of each quenchants for the probes of cylinderical, spherical or square shape, the cooling rate is greater square, cylinder and sphere in order. Coolingability of sodium aquious solution of NaCl, Na₂CO₃and NaOH is found generally greater then that of distilled water. Effectiveness of ingredients is in the order of Na₂CO₃, NaOH and NaCl. In both solutions coolingability increases in 20%, 5%, and 10% in order. Analytical results obtained from Finite Element Method were compared with experimental ones and found as practically satisfactional.