Abstract:According to the principle of mathematical drawing of Bezier curve,the smooth and natural CCT curve could be obtained by using cubic Bezier curve drawing method when analyzing the actual measurement and drawing the CCT curve of super cooled austenite continuous cooling transformation of steel. According to the trend of several transition points before and after the critical rate,the approximates mooth curves could be obtained by using differential approximation method to deal with the intersection of the extension lines of two groups of phase transition connectors with different structures. Inaddition,according to the actual production needs,the datas of 10-15 groups of experiments could be used to draw the smooth CCT curve which could meet the production needs. Based on this,the CCT drawing soft-ware AutoCCT system was developed,and it was well applied in the actual test rendering.