Abstract: Optimizations of initial carbon and oxygen condition，blowing oxygen time, exhausting system, and liftgas flowrate pattern were conducted to develop an effective decarburization process for 180 t RH degasser. The initial carbon mass fraction was kept between (250-500)×10^-6，and oxygen mass fraction between )=（300-650）×10^-6；the pressure in the vacuum chamber quickly decreased to less than 150 Pa；when the initial condition w(C)/w(O)>0.66，oxygen was blew to force decarburization at eaaly；the lift gas was 1.0G m³/h（0~4 min），0.8G m³/h（4~6 min），1.0G m³/h（after 6 min）.With the new process largescale industrial production results indicated that a majority of final mass fraction of carbon could be reach to less than 15×10^-6 in 15 min.

Key words: RH, decarburization, decarburization rate, optimization