This work compared the densification behavior and pores evolution of two kinds of samples (15% and 35% initial porosity stainless steels parts) prepared by selective laser sintering. The results show that post microwave sintering process results in an increase of the density of sample. At the low sintering temperature (1200°C, 1300°C), the low porosity can lead to high density in the final sintered sample. As the sintering temperature reaches 1400°C, however, the sample with 35% initial porosity could be sintered to the higher final density than that of the sample with 15% initial porosity. The results also indicate that the initial porosity has a great effect on the number of pores, pore size, pore shape and the distribution of pores during post sintering process.