Abstract: In view of the steel tube produced by "EAF-LF-VD-HCC" horizontal continuous casting process, micro and large inclusions in the steel before and after LF, after VD, in tundish and casting blank were studied by using optical microscope, scanning electron microscope, EDAX energy dispersive spectroscopy, electron microprobe, electrolysis, tracer tracking and other analytical tools and methods. The results show that the relative numbers of tube steel micro-inclusions and macro-inclusions are 16.1 mm^-2, and 214.6 mg·kg^-1, respectively.