Inclusion and transversal impact toughness of 14 mm plate of steel 09CuPTiRE with adding 0.042% RE or feeding CaSi wire-adding 0.042%RE after Al deoxidation have been studied by a 50 kg vacuum induction furnace. Re-  sults showed that ysth adding RE treatment

the RE yield was 12% with0.005% RE in steel and RE/S =1.0

the inclu-  sions in steel were RE oxysulphide and RE oxide and the average transversal impact energy at 20 ℃ of plate was 112 J;  with feeding CaSi wire -adding RE treatment

the RE yield was 31% with 0.013%RE in steel and RE/S = 2.2

the in-  clusions in steel were compound of spherical calcium silicate and RE oxysulphide and the average transversal impact energy  at 20 ℃ increased to 130 J. The feeding CaSi wire -adding RE process was better than only adding RE process.