The　dynamic　characteristics　of　SAPO-34　and　ZSM-5　zeolite　in　the　desorption　process　have　been　experimentally　studied　with　the　gravimetric　method.　The　weight　change　of　the　test　sample　was　recorded　continually　for　different　conditions　of　temperature　and　pressure.　The　curve　of　the　desorption　degree　with　the　temperature　and　the　pressure　was　obtained　and　discussed.　With　the　intrinsic　different　microstructure,　the　two　zeolites　showed　distinguished　characteristics　of　the　desorption.　In　contrast　to　an　S-shaped　desorption　curve　of　the　SAPO-34,　the　ZSM-5　showed　an　exponential　desorption　curve.　In　comparison,　the　desorption　characteristics　of　the　ZSM-5　were　better　than　that　of　the　SAPO-34　in　the　temperature　range　of　40　degrees　C　similar　to　90　degrees　C.　Nevertheless,　the　effect　of　the　pressure　on　the　desorption　degree　was　stronger　for　the　SAPO-34　than　for　the　ZSM-5.　Further　analysis　revealed　that　the　desorption　speed　was　affected　more　strongly　by　the　temperature　than　by　the　pressure.