Microstructure and pitting corrosion behavior of base metal (BM), heat-affected zone (HAZ), and weld zone (WZ) in the 316L stainless steel weld joint was investigated. The results indicated that WZ, including ferrite and austenite phases, was mainly composed of columnar dendrites, while BM and HAZ exhibited a full-austenite structure with low Sigma coincidence site lattice boundaries especially twin boundary primarily. No obvious pitting occurred in WZ, while the millimeter-scale pits were observed in HAZ and BM after immersion test in 6% FeCl3 solution. HAZ had a lower pitting potential than WZ and BM, while not much difference in pitting potential was observed between WZ and BM. Dendrite-selected corrosion occurred in WZ, while grain boundary was the preferable site for pitting corrosion in HAZ and BM. Gain refinement and a decrease in twin boundary volume fraction promoted the pitting corrosion susceptible of HAZ.