Abstract: The surface cracks on the 300 mm×360 mm continuous casting bloom of low carbon and high manganese steel made by electric-arc furnace(EAF),ladle furnace(LF),and vacuum decarburization(VD) processes were found after cooling. The formation of surface crack was investigated by optical microscopy,scanning electron microscope(SEM) and energy dispersive spectrometer(EDS). The results indicated that surface crack was related to the chemical composition of the steel,the inclusions,the temperature of the steel,the mold fluxes,and the precipitates. Controlling the chemical composition of the steel,decreasing the amount of inclusions,controlling the temperature of the steel reasonably,and using special mold flux can promote the surface quality of the casting bloom in some degree.