The complexity of known phenomenon of cavitations in hydraulic structures is due to different experiences in damage observation and varied effective factors influencing on cavitations initiation. The effective parameters on damage in the dam spillway, are flow velocity, system pressure and surface material strength, operation time duration and air content. In classical damage controlling method, capitation index was used. In this research the fuzzy logic was applied to arrange the damage levels, management and prediction of damage intensity, depending on two important factors, velocity and cavitations index. Verified numerical data of two spillway cases, reported real data, classical predicted damage, and predicted result of a prior fuzzy modeling were used in order to develop and verify the new fuzzy model and test it. The developed model estimated cavitations damage level similar to real damage intensity and predicted damaged region close to the real damaged zone.