With the rapid development of fundamental construction, natural sand resources is getting less and less, artificial sand has become a new kind of sand source. Artificial sand’s production can produce a certain amount of aggragate micro-fines, rational use of micro-fines will be an important factor about affecting application of artificial sand. In this paper，impact of fineness and volume of artificial sand on cement and mortar performance is studied systematically, provides technical basis for the effective use of micro-fines. The experimental results show that micro-fines decreases water requirement of normal consistency and shorten setting time of cement, appropriate fineness micro-fines will reduce water requirement, improve strength, less shrinkage of mortar. The pore structure results show, finer micro-fines refines the pore structure, reduces the porosity of mortar.