Abstract: The operation process simplicity and high operating efficiency allow the phased fracturing technology for open hole horizontal wells to be widely used in the stimulation of low?porosity, low?permeability and low?pressure reservoirs. The key of it is the open hole completion tools of which packer and sleeve are the important part. On the basis of previous studies, the structures and working principles of he well completion tools are analyzed, the open hole induced fracture initiation model for the horizontal wells is developed, and the formula about the fracture initiation model is derived. Combining with formulas of string friction, perforation friction and hydrostatic pressure, the heoretically calculated breakdown pressure is consistent with that in the fracturing operation curve. Finally, the main factors of influencing sleeve open are analyzed by the calculated staged fracturing fracture?initiation pressure