The geometrical shape and surface morphology of recycled fine aggregate from clay brick（RFCB） were assessed， and the influence of particle size distribution and initial water saturation of RFCB on the rheology behavior and mechanical properties of concrete was explored. The results indicate that compared to natural river sand， the geometrical shape of RFCB shows irregular shape as well as lower morphological index， and the surface morphology of RFCB exhibites undulation topography with concave and convex as well as higher roughness value. Due to the complexity of physical characteristics of RFCB， both the yield stress and plastic viscosity of fresh concrete are increased， and the splitting tensile strength of hardened concrete is enhanced， but it has no significantly adverse effect on the compressive strength. Optimally reducing the minimum particle size and initial water saturation of RFCB result in a poor rheological behavior of fresh concrete， but it helps in forming soft core of inner RFCB and stiff shell of outer interface， thus enhances the mechanical properties.