Abstract: Using the independently developed intelligent software the content of Ti and N in the 20CrMnTi carbonization steel was optimally designed.The size and distribution of the austenite grains and second phase particles after composition optimization were measured by optical microscope,SEM and its accessary EDS.The surface contact fatigue life of the steel was measured through contact fatigue experiment.The results show that the austenite grains in the steel after composition optimization designed using the software would not grow obviously during the carburizing process,at the same time the liquid-extraction of TiN was basically eliminated,and thus the contact fatigue life of the steel was improved significantly.