Abstract: Based on the theory of multi-layer composed thick-wall cylinder, the elastic-plastic analysis of the casing-concrete sheath-rock combination was made. The equations for expressing the distribution of stress in the combination under elastic and elastic-plastic conditions were deduced. Also the characteristics of the force on the composed cylinder in the different working status such as elastic and plastic conditions were analyzed. The research results show that the ideal property of concrete sheath should be of high strength and low stiffness. The high strength of concrete sheath could resist higher loads of formation stress. At the same time, the low stiffness of that could reduce the transfer coefficient of stress greatly. From this point, the development of new type plastic concrete with high strongth and low stiffness should be enhanced.