Abstract: In order to improve the inner quality of heavy slab, one type soft reduction technology which dependented on pressure control was developed, and dynamic casting machine soft reduction without solidification model control condition was achieved. The controlling means was established by writing PLC control program that the system could calculate the cylinder feedback pressure of segment in real time，and compared with the statistical pressure standard values in production in realtime, and the pressure standard values range was reached by controlling the roll gap of the caster segment. The results showed that the ratio of centerline segregation above level C2.5 of the slab improved from 75% to 90%, and the ratio of center crack below 0.5 increased from 50% to 80%.

Key words: centerline segregation, feedback pressure, soft reduction, inner quality