Significant　flexoelectricity　is　expected　to　exist　in　materials　with　colossal　permittivity.　Here,　we　systematically　studied　the　interplay　of　flexoelectricity　and　permittivity　in　CaCu3Ti4O12　(CCTO)　ceramic　by　examining　the　thickness　and　electrode　dependence　of　the　flexoelectric　coefficients　over　a　wide　range　of　temperatures.　We　found　that　an　abnormal　flexoelectric　transition　occurs　at　95　?.　Below　this　critical　temperature,　the　barrier　layer　mechanism　dominates　the　significant　flexoelectricity　in　CCTO　ceramic,　whereas　above　this　critical　temperature,　the　flexoelectric　response　mainly　originates　from　the　contributions　of　semiconducting　grains　and　insulating　grain　boundaries.　The　observed　flexoelectric　transition　is　beneficial　not　only　for　developing　new　materials　with　high　flexoelectric　coefficients　but　also　for　understanding　the　colossal　permittivity　mechanism　in　CCTO　ceramics.