Abstract: Selective laser melting has been applied to fabricating 18Ni300. Using SPSS（ Statistical Product and Service Solutions） and various testing equipment to study the dimensions,roughness and density of specimen with different fabrication angle. Meanwhile,ageing treatment was applied,and its influence on the quality and shape were analyzed. The result shows that the dimensions of specimen become smaller than the designed dimensions. The specimen becomes wider and thinner with the fabrication angle being larger. Roughness increases firstly and then decreases with the fabrication angle being larger. However,Density first decreases and then increases with the increase of the fabrication angle. Though ageing treatment cannot make any changes on the dimension of parts,it can result in the improvement on roughness but decrease of density.