The steel-making system is a discrete and continuous process, which includes many types of equipment and is affected by many factors. The key factors to cast in a constant speed are steel temperature, transportation of the steel in converter steelmaking, secondary refining and continuous casting process. The constant casting speed technology is required for good condition equipment, scientific production process and optimized production routine. With the development and application of constant casting speed technology in Qian’an steel company, the constant casting speed ratio is already stable at 97% by optimizing the production process, strengthening the process controlling ability and scientific, stable, efficiency production organization. Million tons of liquid steel was casted without mold breakout.