Abstract: The damage propagation property of Ultra-high toughness cementitious composites (UHTCC) was studied using three-point flexural fatigue tests on single-notched specimens. Based on the continuum damage mechanics and the flexural fatigue damage model, two fatigue damage propagation models were built. One was a bi-logarithmic linear model with J-integral range as its independent variable. The other was a semi-logarithmic linear model with fatigue stress level as its independent variable. Results from the two models fit well with experimental results. However, because the J-integral is strongly dependent on the specimens' geometry, the first model was affected significantly by the specimens' shape. The second model is expected to be more applicable in engineering practice since the fatigue stress level is easy to obtain.