Abstract: The thermal dissociation scope of gas hydrate in depositaround heat conductor is very important for either gas hydrateexploitation or related hazard prevention. Maximum dissociation scope based on planarheat dissociation under the boundary condition of constant temperatureis obtained and compared with that obtained in heat dissociation experiments of THF hydrate indeposit in this paper. It is shown that the maximum dissociation scope isdetermined by the difference between the temperatures of heat source andsurrounding environment. The theoretical results of the maximum dissociationscope are in agreement with those of experiments, with errors less than5%.