Cephalopods play the key roles in marine ecosystem as important invertebrate in the ocean. However, little information about its predation and dietary status has been known so far. As a novel applied technology, stable isotope has multiple utility functions with quick inspection and accurate result, so this method is applied in many researches including marine ecosystem. A large proportion of carbon, nitrogen and oxygen are accumulated in the body of cephalopods, which are both predators and food of top predators. The hard structures are the good carrier of the elements for stable isotope. Therefore by means of stable isotope tracing, the content and distribution of stable isotope in every section of hard issue is analyzed to understand the trophic level of cephalopods among the marine organism. In this paper we will give a brief introduction of the application of stable isotope in hard issues of cephalopods (such as statoliths, beaks and inner shell), give a comprehensive understanding of trophic ecology on cephalopods and have a looking in the future.