In view of the fact that certain new regulations concerning international conventions are going into effect, the matter of stability has become one of the keys in the design of double-bottom and double-skin oil tankers. Should the conventional method still be adopted to check the stability of the double-bottom and double-skin tankers, the result would be that stability would not meet the above-metioned new regulations so that we would face the following unpleasant situation : either alter the cargo tank arrangement or exert the limits on the load. The author has found out in his practice of design that it is not quite resonable to apply the conventional calculation method to the check of the stability of double-bottom and double-skin oil tankers. Therefore, the stability calculation method for such oil tankers has been probed into, and a corresponding calculation method has been worked out.