Abstract: 316L austenitic stainless steel was surface enhanced by low temperature gaseous carburization, and then aged at 300-400 ℃ for 150, 1 500, 3 000 h, respectively. The effects of aging temperature and time on phase composition, thickness, nano-hardness and residual stress of the carburized surface layer were investigated. The thermal stability was analyzed. The results show that no new carbides precipitated in the carburized layer during aging at 300-400 ℃. When aged at 400 ℃, carbon atoms diffused into the substrate, leading to an obvious thickness increase of the carburized layer. The interface between the carburized layer and the substrate disappeared, and the surface nano-hardness decreased to 50% that of substrate after aging at 400 ℃ for 3 000 h. When aged at 300 ℃, the thickness, carbon content and nano-hardness of the carburized layer changed little; the carburized layer was relatively stable during working at 300 ℃. After aging at 300-400 ℃, the surface residual compressive stress of the carburized layer decreased, and the decreasing amplitude was larger at a higher aging temperature or for a longer aging time.