River sand was replaced by aeolian sand partly in concrete to study the influence mechanism of aeolian sand on the strength of concrete. The internal pore structure of aeolian sand concrete was tested by nuclear magnetic resonance(NMR), the initial damage of bearing surface was detected by the slicing of CT and the structural form of interface transition zone(ITZ) and the hydration product microstructure were characterized by scanning electron microscopy(SEM). A concrete strength prediction model considering the fineness modulus or specific surface area of sand changing was built based on the American ACI model. The results show that the concrete has the highest strength with an aeolian sand content of 20%. The influence mechanism why a proper amount of aeolian sand increases the strength of concrete is that it optimizes the particle gradation of aggregate, improves the internal pore size distribution and the ITZ structure of concrete, as well as reduces the initial damage of the bearing surface. The theoretical prediction model agrees well with the experimental results.