The invention provides a multi-stage staged fracturing sliding sleeve. An upper sleeve and a lower sleeve are arranged in a sliding sleeve outer tube, a hole is sealed by the lower sleeve, and the lower end of the upper sleeve is rested at the upper end of the lower sleeve. An open annular ball seat is arranged in the upper sleeve, and a broken opening is formed in the side wall of the open annular ball seat, so that the open annular ball seat can be in an open state or a contracting state. When the open annular ball seat is in the open state, the outer wall of the open annular ball seat is attached to the inner wall of the upper sleeve. A stepped hole with an upper section and a lower section is formed in the lower sleeve, the diameter of the upper section hole of the stepped hole is identical to the outer diameter of the open annular ball seat in the contracting state, and the diameter of the lower section hole of the stepped hole is smaller than that of the upper section hole, so that a step part is formed. A first bevel chamfer is arranged on the edge of the upper end hole of the stepped hole, and a second bevel chamfer is arranged on the bottom edge of the outer wall of the open annular ball seat. The inclinations of the first and second bevel chamfers can promote the open annular ball seat to slip into the stepped hole along the first bevel chamfer. The requirement of subdividing certain layers can be met in the staged fracturing process.