The selective laser melting of a blended powder system consisting of 96wt% 316L stainless steel and 4wt% NH4HCO3 was performed to prepare porous materials. The SEM characterizations show the formation of a honeycomb-like porous structure at a relatively high laser power of 800 W. The pore sizes of the porous structure distribute homogeneously, typically in a range of 2-5 μm. The average pore size is about 3.5 μm. The effects of laser power on the microstructural characteristics of the as-obtained microcellular structures were investigated. The formation mechanisms of the honeycomb-like porous structure during selective laser melting were also discussed.