Under-pressure dragging type separate-layer fracturing device

The utility model discloses an under-pressure dragging type separate-layer fracturing device, which comprises ground equipment and a downhole tool string. The downhole tool string comprises a conical stopper, a packer, a hydraulic spray gun, a collar-type tubing, a wear-and-corrosion-resistant check valve and a collar-free tubing, wherein the conical stopper, the packer, the hydraulic spray gun, the collar-type tubing, the wear-and-corrosion-resistant check valve and the collar-free tubing are sequentially connected together. The ground equipment comprises a wellhead cross joint, a dual-flashboard blowout preventer, a blowout stuffing box and an anti-jacking air slips. The upper end of the collar-free tubing is connected with a lifting pipe nipple. The lifting pipe nipple is suspended by means of an elevator and the large-hook hanging ring of a workover rig. The hanging ring is capable of moving up and down. The collar-free tubing is dragged to slide within the blowout stuffing box. The lifting pipe nipple is connected successively with a high-pressure elbow and a high-pressure hose line. The high-pressure hose line is connected with a ground high-pressure steel pipe line of a fracturing multi-unit 1. The steel pipe line is provided with a high-pressure tee. The high-pressure tee is provided with a plug valve for the pressure release of pipelines. The wellhead cross joint is connected with a fracturing multi-unit 2. Due to the combination of the dual-flashboard blowout preventer, the blowout stuffing box and the collar-free tubing, a tubing string is directly lifted upwards at a wellhead under pressure by means of a conventional workover rig, and the sand-sticking risk of the tubing string can be reduced maximally. Meanwhile, the layered fracturing efficiency and the cost performance are improved greatly.