Abstract: The structure of the setting ball seat used in the vertical well fracturing is very single, and the seat conventionally used in the horizontal well has some limitations in meeting the requirement of construction technique for staged fracturing in horizontal wells, so a special setting ball seat is developed. these ball seat not only can achieve the perfect sealing between ball and ball seat, but also make the ball seat self-sealing come true to avoid the problem that the whole string can not be sealed because of the unfixed setting ball at the horizontal section. This technique was implemented in 4 wells in Sulige gas field. The sealing of hanger packer, the expanded sealing of open hole packer, and the hydraulic releasing of hanger packer were all successfully completed at strings of horizontal well fracturing. It shows that the Ball Seat Sub with stable performance can meet the requirement of horizontal well fracturing.