The invention discloses a down-hole multi-stage separate-layer-fracturing switch device. The down-hole multi-stage separate-layer-fracturing switch device is designed for solving the problem that opening success rate of a slide bushing is low in the operation process of oil field multi-stage separate-layer-fracturing measures. The down-hole multi-stage separate-layer-fracturing switch device comprises a first outer sleeve, a second outer sleeve, a ball rod, a first seal ring, a second seal ring, a third seal ring and the like, wherein the first outer sleeve is connected with an upper joint, the second outer sleeve and the ball rod are connected with a slide bushing core, the first seal ring is located at the point where the upper end face of the slide bushing core and the second outer sleeve are matched with the upper joint, the second seal ring is located at the point where the slide bushing core is matched with the lower end face of the second outer sleeve, and the third seal ring is located in a sealing groove formed in the neck of a conical head type ball rod. The device is placed at a to-be-operated layer of a shaft along with a measure operation pipe column, after the measure operation at the lower layer is finished, the ball rod is thrown in to open an operation channel at the upper layer, and fracturing fluid is pressed into stratums through the opened channel to complete measure transformation. Channels at different layers can be opened by throwing different ball rods to achieve separate-layer fracturing through one pipe column, the operation cycle can be reduced, and the maintenance operation cost can be reduced substantially. By means of the device, the slide bushing is still sealed when entering a carrying barrel, the opening success rate and the safety of the switch device can be improved, and the device is an ideal tool for transformation and production of low permeable reservoirs in oil-gas field development.