A dry friction oscillator driven by a moving belt, whose velocity could be continuously controlled, was investigated under the assumption that the dry friction force was constant and the excitation frequencies were harmonic. And the codimension-1 sliding bifurcation of Filippov system was analyzed and numerically simulated. The numerical simulation reveals that there are abundant bifurcation phenomena, and that smaller excitation frequencies tend to cause non-smooth sliding bifurcation in the dry friction oscillator system.