Abstract: Taking the 170 t RH refining equipment of a steel company as a prototype,a mathematical simulation of flow field in the RH is carried out to study the dead zones in the RH melt bath under different gas flow rates,inner diameter and immersion depth of snorkel and vacuum degree.The results show that there are three dead zones at the top of ladle.With the increase of gas flow rate,the dead zones 1^# and 3^# get smaller rapidly and the zone 2^# gets larger at the beginning until the largest zone appears at 100 m³/h and then becomes smaller;with the increase of the diameter of snorkel,all the 3 dead zones get smaller and a long narrow dead zone forms below the two snorkels in zone 2#;the deeper the snorkel inserts,the larger the dead zones get and the more steady the surface of the ladle becomes.Among these operational parameters contributing to decreasing dead zones,the gas flow rate is the most influential factor,while the vacuum degree is the least.