The strength reliability of the PSZ ceramics with grinding damages under cyclic loading is evaluated by the crack growth parameters of grinding damage model, which is estimated from the result of fatigue testing. The result of cyclic four point bending test of ceramics specimens with grinding surface shows that the fatigue characteristics depends on the initial crack length and density of cracks caused by grinding. In order to estimate the model of cracks on grinding surface, the initial crack length and the length of crack growth during cyclic bending is measured from the fatigue fractured surface. Also the density of cracks is assumed from an approximated life curve at the fatigue characteristics. And then the crack growth parameters m, C and fatigue fracture toughness value Kfc are calculated using the estimated model of cracks. Further, statistical characteristics of the crack growth parameters for the ceramics with multiple cracks are expressed by Weibull distribution function in the ceramics with single cracks. The evaluated strength reliability agrees with a fatigue characteristics of ceramics with grinding surface under cyclic four point bending. Therefore, it is found that the proposed method in this study is sufficiently effective for the strength reliability evaluation of ceramics with grinding damages.