[en] Acquiring the special information about measured object by gamma spectrum has important application in the field of arms control verification. The geometry information of the shield material out of source has been obtained by several group of intensity ratio of different energy gamma rays, which would reduce the affect for the evaluation of the inner assembly characteristic when the packaging is unknown. In this paper, the method of analyzing the thickness of several layers shield materials has been established, and the thickness of several layer shield materials out of plutonium source and ¹⁵²Eu source has been analyzed based on the experiment, the result of the ¹⁵²Eu source is better than the plutonium source obviously, the reason of the disagreement between the experiment result and the actual value has been analyzed. (authors)