Abstract: In this paper, the method and algorithm of multi-sensor decision-making level based on D-S evidence theory are researched in the light of basic theory knowledge of the multi-sensor information fusion, and the detailed formulations are reasoned without middle normalizing unity calculation with extending Dempster rule to multi-source information, which can reduce the calculation quantity. When this method is used to the nondestructive testing experiment that three kinds of sensors detects a casting, the result has proved this improved algorithm can improve detection precision and speed.