Based　on　the　calculation　methods　of　nominal　water-cement　ratio　of　mortar　and　average　paste　thickness　of　standard　sand　provided　by　authors,　the　nonlinear　relation　between　fluidity　of　mortar　and　nominal　water-cement　ratio　of　mortar,　average　paste　thickness　of　standard　sand,　fly　ash-binder　ratio　was　established　by　using　artificial　neural　network　(ANN).　The　outcome　of　this　paper　can　be　used　in　determining　the　effect　of　water　reducer,　and　lays　the　foundation　for　the　prediction　of　concrete　slump　and　the　mix　proportion　design　of　higher　volume-stability　concrete.