Abstract: The main source,quantity,size distribution,composition and type evolution rule of non-metallic inclusions in SPHC steel were analyzed and studied through the castig sampling of Tangsteel FTSR cold rolling base material （SPHC） steel,and the inclusions was scanned and detected automatically by ASPEX.The results showed that the inclusions were mainly Al₂O₃ after feeding aluminum line,and MgO-Al₂O₃ type inclusions were formed in molten steel during the refining process.The inclusions whose length larger than 5μm were about 15% after feeding aluminum line and inclusions floatation. After calcium treatment,the Al₂O₃ and MgO-Al₂O₃ inclusions had better deformation effect,and the inclusions were changed into CaOCaS-Al₂O₃ compound inclusions,the inclusions less than 5 μm were more than 95%. Based on these findings,The countermeasure such as optimizing slag-making and argon blowing system,optimizing production organization mode and raising the level of protection casting had been utilized,and achieved the purpose of reducing the inclusion content,shortening refining cycle,reducing the production cost.