In order to prove the reserves of gas hydrates, the method that how to achieve the truth-preserve sample is one of the key technologies. The wire line sampler for gas hydrates by hole bottom freezing is designed, that the dry ice freezing method is applied. The parameter, freezing method principle, general structure, operating principle and structure features of sampler is researched. The study has shown that wire-line sampler for gas hydrates by hole bottom freezing can satisfy with the truth-preserve of gas hydrates demands, and it supplies the news ideas for the design of gas hydrates truth-preserve core sampler.