In this paper, an S-130 MSS is successfully produced by SLM. For SLM as-deposited samples, the phase analysis reveals a large amount of martensite and a small amount of retained austenite, and the microstructure is characterized by the cellular dendrite structures and a large number of martensite laths. After the two kinds of heat treatments, the formation of reverted austenite increases the content of austenite, and a large number of nanosized precipitates are uniformly dispersed in the martensite laths. Meanwhile, the lamellar retained/reverted austenite is distributed among the martensite laths. Compared with those of the SLM as-deposited samples, the microhardness and tensile strength are significantly improved and the elongation is not reduced after two kinds of heat treatments. Moreover, in comparison to that after five-step heat treatment, the sample after three-step heat treatment possesses a high content of austenite and slenderer martensite laths as well as finer precipitate, which contributes to high microhardness and tensile strength under the condition of ensuring elongation. The optimized heat-treatment regime for the SLM as-deposited S-130 MSS is three-step heat treatment (solution+ cryogenic cooling+ aging).