Abstract:In order to study the influence of the quality and content of fiy ash on the cracking behaviors of concrete, the modified fiatype specimen was used. The effects of particle size distribution and oxide component of fly ash on the optimal content for the cracking behavior of high-flowing concrete were studied by grey connection analysis. The results indicate that when the particles size are smaller than 20.4 μm, there are positive effect on the optimal content of fly ash for the cracking behavior of highflowing concrete. Properly increasing the content of MgO, K2O, CaO and SO3 and decreasing the loss on ignition may raise the optimal content of fly ash for the cracking behavior of high-flowing concrete.