A mathematical model to show the dynamic response of the mold oscillator was suggested.The model considered a frictional interaction between the mold oscillator and slab as several connected nodes.The governing equation considered the slab as a multi-degree-of-freedom(DoF)system,and included a hysteresis model to describe elastic-plastic behavior of the slab;the mold oscillator was given two DoF by utilizing pressure and displacement experiment data.Simulations indicate that the mold and slab execute various vibrations,and that mold oscillation marks are caused by a stick-and-slip phenomenon during intervals,in which the slab contacting the mold moves downward compared to the other slab(negative strip time).The slab shows the formation of mold oscillation marks to previous formation criterion equally when the mold velocity is faster than the casting speed about downward.The oscillation mark will grow up over 2 Hz exciting frequency with constant 4 mm stroke in simulations.Finally,the negative strip time was compared to the frictional force,hysteresis variable,and plastic force to investigate formation mechanism of the oscillation marks. A mathematical model to show the dynamic response of the mold oscillator was suggested. The model considered a frictional interaction between the mold oscillator and slab as several connected nodes. Governing equation considered the slab as a multi-degree-of-freedom (DoF) system, and included a hysteresis model to describe elastic-plastic behavior of the slab; the mold oscillator was given two DoF by utilizing pressure and displacement experiment data. Simulations indicate that the mold and slab execute various vibrations, and that the mold oscillation marks were caused by a stick-and-slip phenomenon during intervals, in which the slab contacting the mold moves downward compared to the other slab (negative strip time) faster than the casting speed about downward. The oscillation mark will grow up over 2 Hz exciting frequency with constant 4 mm stroke in simulations. Finaally, the n egative strip time was compared to the frictional force, hysteresis variable, and plastic force to investigate formation mechanism of the oscillation marks.