In order to solve the problem of stone powder reuse in the process of sand production,we study the influence of sandstone powder on mechanical properties of mortar.By means of XRD DSC-TG,SEM and MIP,we analyze the influence of sandstone powder on the morphology and pore structure of hydration products of cement mortar.The results show that the mechanical properties of the mortar increase with the increase of the content of sandstone powder when the content of stone powder does not exceed 11%.With the increase of the content of sandstone powder,the mechanical property of the mortar gradually improves,while the porosity,median pore diameter,maximum aperture and average pore diameter of the mortar reduce.It proves that the stone powder can optimize the distribution of the pore structure of the mortar.The CaCO3 of the sandstone powder can react with C3A,and the reaction product is C3A·CaCO3·11H2O.Particle filling effect and chemical activity of sandstone powder are the main reasons for the improvement of the mechanical property of slurry.The results may serve as reference for the preparation of sand concrete and reuse of stone powder.