Abstract: The depth distribution of kick off points is one of the key factors to determine the anti-collision design effect of the dense cluster well group, while its depth range- kick off window is the premise of a rational allocation. To this end, analyzed the trajectory of 152 wells which designed with long vertical section close to 900 meters, obtained its horizontal displacement deviation, established its probability model, formed a method which can be used to determine the kick off window of dense cluster well group. Through the design and drilling in NP1-3 manmade island which with dense cluster well group, the method be proven that it can provides a relatively reasonable kick off window to NP Oilfield with dense cluster well group.