Serial sectioning was carried out in two stainless steels (type 304 and 316), and EBSD was used to characterize these sections.The analyzedvolume of each case is about 600μm× 600μm× 300μm with a spatial resolution of about 2.5μm×2.5μm×2.5μm, which is fine enough for the material with a 40μm mean grain size.The software: Dream 3D, Pare View and MTEX-Matlab, were used to reconstruct and visualize the 3-dimensional (3D)microstructure of grains and the inter-connected grain-boundary-networks (GBNs).3D morphology of the grains and their orientation relationships were analyzed to interpret the topology of the GBNs by paying attention to the triple-junction-lines and quadruple-junction-points.The morphologies of annealing twins were classified into 4 typical categories according to the 3D observations.The grain volume distributions were measured and showed a very different distribution than the grain size distribution as measured on a 2D section.These 3D EBSD characterization results facilitate a more comprehensive understanding of the microstructure of stainless steels.