The combination of powders with different particle sizes plays a vital role in the quality of samples formed by selective laser melting. In this paper, the effect of IN738 alloy with different particle size powders on the powder characteristics and the quality of the shaped parts have been systematically studied. The results show that the powder fluidity increases with the increase of the volume fraction of the large particle size powder. When powders with large and small particle sizes （50% particle size of 31 μm to 53 μm and 50% particle size of 15 μm to 30 μm） are matched with each other, the particle size distribution shows that D10 is 15.1 μm, D50 is 27.9 μm, and D90 is 52.9 μm, the apparent density and tap density of the powder are higher. And the density of shaped part reaches 99.3%, with the better surface roughness and the lower porosity and crack density. The study exhibits that the cracks of the printed parts are solidification cracks, and the cracks are mainly distributed and propagated along the epitaxially grown 〈001〉 oriented columnar grain boundaries.