Abstract: Since the 11th Five-Year Plan, the Bohai Oilfield has successively carried out a number of integral infilling projects of well cluster pattern in large-scale oilfields.Precise control and collision avoidance of wellbore trajectory are the biggest challenges in the implementation of such projects.After years' exploration and practice, Bohai Oilfield has developed a set of integral infilling and drilling anti-collision technologies of cluster well pattern, including track optimization design, accurate measurement, high-efficiency control, anti-collision monitoring and post-collision emergency treatment.They have been successfully applied to the integrated well pattern adjustment of many large-scale oilfields in the Bohai Sea with anti-collision rate of 100%.The technical system was summarized systematically and the relevant technical regulations were put forward.The research results can provide the reference for the integrated adjustment projects and the adjustment well infilling.