The edge crack and performance fluctuations of door frame Q420C steel for forklift truck appeared in the process of trial production are analysised and researched deeply. By adjusting the composition and deoxidization process,improving inclusion removal and rolling process of steel, reforming rolling equipment moderately , the production process is optimized. The production practice shows that, the quality of Q420C dramatically is improved obviously. The edge crack problems are eliminated.The not full and corner drawing has been controlled effectively.Various performance indicators are to meet product quality requirements.