The　microchannels　with　triangular　corrugations　usually　have　high　heat　transfer　ability,　but　the　possible　continuous　two-phase　instable　boiling　with　periodically　moving　gas-liquid　interface　may　cause　the　oscillations　of　pressure　drop　and　temperature　of　walls,　and　lead　to　some　control　issues　and　security　risks.　In　this　paper,　acetone　is　chosen　as　the　working　fluid,　and　an　experimental　setup　with　multi-sensors　is　built.　The　straight　and　triangular　corrugated　microchannels　are　applied　for　comparisons　and　analysis.　Both　microchannels　have　same　hydraulic　diameters　of　104.3　mu　m.　After　experiments　at　the　working　conditions　of　G　=　250-1100　kg/m(2)s　and　q(eff)　=　208-1050　kW/m(2),　the　similarities　and　differences　about　continuous　instable　boiling　between　two　types　of　microchannels　are　found.　A　prediction　model　with　equations　and　principles　are　developed,　and　the　wall　temperature　at　inlet　is　chosen　as　the　judging　criteria.　The　analysis　results　show　that　the　wall　temperature　at　inlet　dominant　the　instable　boundaries,　and　which　can　be　affected　by　the　working　conditions　and　structural　parameters.　The　prediction　model　also　indicates　that　the　increasing　of　flow　resistance　at　inlet,　decreasing　of　inlet　temperature　and　heat　transfer　coefficient　at　inlet　can　reduce　the　area　of　instable　boiling　by　about　40%,　and　decrease　the　slopes　of　instable　boundaries　by　24.2-51.7%.