There exists a phase change for hydrate dissociation process during which is accompanied by a density difference, that also known as Stefan moving boundary problem. The conduction equations of the heatdissociation hydrates are derived creatively for a semi-infinite slab reservoir. Based on the Rankine-Hugoniot jump conditions, the moving boundary condition of the dissociation frontier is innovatively deduced from a multidiscipline perspective. Exact solutions are derived in detail for the temperature distribution and the dissociation frontier location. Compared with models of the constant density, laws of the temperature and the frontier location are obtained for a sample hydrate reservoir considering some effect factors, such as various densities, heated-water temperatures and injection times. (C) 2018 Elsevier Ltd. All rights reserved.