Abstract: Based on the UFC-ACC design idea and combining the UFC mechanism with its cooling technological applications in medium/heavy plate production, an optimal UFC schedule was given including different rolling processes with the plates' mechanical properties changed after UFC analyzed. Comparing the metallographic structures obtained from different technological processes and combining them with theoretical calculation, how the structure property of medium/low carbon steel evolves due to UFC was discussed and summarized. It was found that the impact toughness of medium/low carbon steel increases obviously in addition to other mechanical properties which are also improved. What is more, most of the steel structure is homogeneous and fine F+P grains after UFC-ACC cooling with the high dislocation density in original austenite kept on, thus making the steel performance treated by UFC-ACC better than that just treated by conventional ACC cooling.