Obvious changes have taken place in the type, geometry, distribution and amount of non-metallic inclusions after micro-alloyed Ti is added in the steel. The kind of inclusion has been modified from silicate to complex oxide, the geometry has been changed from thick strip to particle, the size distribution obvious changes to the direction of size reducing (<10 mu m), meanwhile, the percentage of inclusion area is reduced gradually. These changes have greatly reduced the destructive degree of inclusion to the continuity of steel base, it helps to improve mechanics performance and anticorrosive performance.