The　fire-exposure　temperature　of　concrete　directly　determines　the　degree　of　damage　to　its　microstructure　and　the　performance　of　concrete.　Therefore,　an　accurate　assessment　of　the　fire-exposure　temperature　of　concrete　is　crucial.　But　to　date,　there　is　not　yet　an　accurate,　practical,　and　effective　method　for　measuring　the　internal　temperature　of　concrete　after　fire.　Based　on　the　discovery　that　fluid　inclusions　in　concrete　act　as　natural　thermometers,　this　paper　investigates　the　scientific　principles　and　experimental　evidence　of　the　decrepitation　thermometry　of　inclusions.　By　extracting　quartz　sand　samples　from　the　interiors　of　concrete　members　after　a　fire　and　performing　an　inclusion　decrepitation　test　on　these　samples,　the　maximum　fire-exposure　temperature　of　concrete　can　be　determined　with　a　high　degree　of　accuracy.　The　test　results　reveal　that　the　natural　sand　used　in　construction　typically　contains　fluid　inclusions,　indicating　that　the　necessary　conditions　for　inclusion　decrepitation　thermometry　are　satisfied　for　concrete　structures.　In　this　study,　standard　quartz　sand　samples　were　configured,　and　inclusion　decrepitation　temperature　measurements　were　conducted　after　subjecting　the　samples　to　different　heating　rates,　cooling　methods,　thermostatic　durations,　and　standing　times　after　fire.　The　test　results　indicate　that　the　impact　of　the　aforementioned　factors　on　the　inclusion　decrepitation　temperature　measurement　is　not　evident.　The　maximum　relative　error　between　all　temperature　measurement　results　and　the　actual　heating　temperature　is　＜10　%,　and　the　average　relative　error　is　＜2.5　%.　The　experimental　results　show　that　fluid　inclusions　are　natural　thermometers　in　concrete.　After　a　fire,　the　maximum　temperature　experienced　in　the　concrete　can　be　quantitatively　assessed　using　the　initial　decrepitation　temperature　of　the　inclusion.　This　method　possesses　the　advantages　of　being　a　scientific　test　method　and　providing　accurate　temperature　measurements　without　any　indirect　analysis　or　calculation　using　simple　test　equipment,　sample　preparation,　and　operation.