Abstract: The microstructure optimization of boron microalloying S31254 super austenitic stainless steel through grain boundary engineering(GBE) and its effects on the intergranular corrosion(IGC) resistance were investigated.The results show that the largest amount of annealing twins appear in the specimen cold-compressed by 9% and then annealed at 1170 ℃ for 10 min.The grain boundary microstructure optimization can be realized through GBE in boron microalloying S31254.Twin boundaries of crystalline boundary engineered treated materials significantly reduce corrosion after a long iron sulfate -sulfuric acid test (48 h).It is confirmed that the twin bound can effectively interrupt the connectivity of stochastic large-angle crystal boundary networks, thus improving the intercrystalline corrosion resistance of boron-microalloyed superaustenitic stainless steel.