Abstract: Based on the full knowledge of the casing service conditions of steam injection wells for dense oil, we designed a kind of heat-resistant & lower dilatation steel. The technical route is adding some kinds of alloy elements and rare earths into Cr-Mo steel to strengthen the grain boundary. The experimental results in laboratory show that it is more advantageous in aspects of high temperature tensile properties and dilatation than C-Mn steel. This steel fits to the service conditions of steam injection wells for dense oil and may be used to the special casing production.