III-V　compound　semiconductor　visible-spectrum　light-emitting　diodes　(LEDs)　have　received　much　attention　for　their　important　applications　in　several　areas.　The　AlGaInP　semiconductor　materials　are　capable　of　emitting　light　of　red　and　orange,　and　the　InGaN　semiconductor　materials　are　capable　of　emitting　light　of　green　and　blue.　Those　four　colors　of　LED　chips　are　encapsulated　with　epoxy　in　same　conditions.　In　this　paper,　the　junction　temperature　of　power　AlGaInP　and　InGaN　LEDs　were　measured　at　different　drive　current　by　forward　-　voltage　method.　Optical　and　electrical　parameters　under　different　temperature　were　also　measured.　Thermal　properties　of　power　AlGaInP　and　InGaN　LEDs　were　analyzed　for　strong　dependence　of　optical　and　electrical　characteristics　of　power　light-emitting　diodes　on　the　diode　junction　temperature.