Abstract: To overcome the difficulties of staged fracturing in horizontal wells in low-permeability reservoirs, such as high breakdown pressure, fracture fluid channeling and high reconstruction cost, the fracturing technique combining hydraulic jet with small-diameter packer is brought forward. The small-diameter K344-108 type packer is developed to match ?139.7 mm casing （internal diameter is 124.3 mm） and the fracturing-drilling tool assembly is designed. Studies have shown that on the basis of cost control, the technique can prevent fracture fluid from channeling and improve the efficiency of staged fracturing. According to the treatment to the horizontal well QP-13, the technique is significant for developing low-permeability and ultralow-permeability tight oil reservoirs in Changqing oilfield with its high operating efficiency and observable stimulating ability.