Abstract: The trajectory design of ERD wells in Veni gas field of Sakhalin area belongs to extra-ERD well, with design well depth about 12 000 m, and the horizontal displacement up to 11 000 m. The operation is so difficult that high requirements for construction design, equipment and material have been proposed. In this paper, several main factors of the borehole trajectory have been optimized to design the drilling hole trajectory, including selection of the KOP, determination of sailangle and optimization of inclined section design methods. On the premise of satisfying the effective development of reservoir, the most suitable design of Sakhalin extra-ERD directional well trajectory has been determined in order to lower the torque and friction, and reduce the operation difficulty.