Abstract: Described are the R & D of oil casing for well-drilling service,covering such aspects as design,manufacture,experiment and operation. The experimental result shows that with the casing connection type featuring buttress thread and anti-torque shoulder the connection is strong enough to transmit the tremendous torque as occurs during well-drilling process,and the shoulder is capable of resisting against the severe torque which is much bigger than that as borne by the thread section. Moreover,with good tightness the developed connection is satisfactory to the technical requirement for the well surface casing.