Abstract: The paper introduces the development of the water-quench heat treatment of oil-well tubulars by Baosteel Co., Ltd., focusing on the water-quench process proper and the straightness, hardness uniformity and mechanical properties of the water-quenched steel tube. The research result shows that the Baosteel-produced oil-well tubulars heat treated with water-quench have been up to relevant world level in terms of internal quality.