The　title　complexes　shown　as　[Fe　3O(C　6H　5COO)　6(H　2O)　3]Cl　·　1.5H　2O　and　[Fe　4O　2　(C　6H　6COO)　7(bipy)　2]ClO　4　·　3.5H　2O　were　prepared.　Their　thermal　decomposition　process　was　studied　qualitatively　and　quantitatively　by　means　of　thermogravimetric　analysis　and　infrared　spectroscopic　measurement　of　samples　after　heating　at　different　temperatures.　From　the　experimental　results,　the　possible　thermal　decomposition　process　of　the　two　compounds　can　be　deduced.　Additionally,　according　to　the　fact　that　the　v　as　(COO)　of　the　two　compounds　decreases　while　the　v　s(COO)　remains　unchanged　as　the　heating　temperature　increases.　It　can　be　drawn　that　the　carboxylate　coordinative　form　possible　change　from　bridged　to　chelate　one.