Abstract: To control longitudinal surface crack of 410 stainless steel billet，a few measures were employed such as composition optimization of molten steel, water flow rate adjustment of mould, chemical and physical properties improvement of mold powder and casting speed optimization，which was following the formation mechanism of surface longitudinal cracks of 410 stainless steel. As a result, the longitudinal surface cracks of 410 stainless steel was effectively controlled, production accidents as breakout were mainly avoided.Surface quality of slab was greatly enhanced，the surface longitudinal cracks in slab was decreased from 11.24 % to 2.18 %，the recondition rate of casting slab was reduced by 3.4 %.

Key words: surface longitudinal cracks, hypo-peritectic steel, mould, heat flux density