Abstract: Based on the inclusion tracer method,all aspects of the converter-continuous casting process adopted by iron and steel enterprises during produced Q235B steel production had been researched systematically. The results show that strand has high inclusion content level and strong reoxidation. Microscopic inclusions mainly consist of SiO₂-Mn O-MnS,SiO₂-Mn O-MoO₃ composite and no Ce and La has been measured,however,tracers of Ce,La,K,Na have been found in most of macro inclusion,which implies that macro inclusions mainly come from the tundish covering flux,mould flux and ladle slag. For reducing the big inclusion content which has the worst effect on the steel quality,the structure of the tundish and the submerged entry nozzle should be optimized,the casting technology should be more stable,at the same time the met allurgical properties of the supplementary material should be optimized to fit for the current casting.