In　this　study,　FeCrNiCoMo　maraging　stainless　steel　was　fabricated　by　laser　melting　deposition.　The　initial　nonequilibrium　microstructure　exhibited　cellular　segregation　of　Cr　and　Mo　with　a　10-20　mu　m　cell　size.　We　investigated　the　microstructural　evolution,　particularly　during　aging　with　different　time(1　h,　3　h,　5　h),　for　three　post　heat　treatments:　direct　aging　(500　degrees　C)　and　low-temperature　solution　treatment　(750　degrees　C)　and　aging　without　and　with　additional　prior　homogenization　(1000　degrees　C).　Microsegregation　profoundly　affected　the　austenite　reversion　behavior.　The　segregation　at　the　cell　walls　promoted　the　nucleation　and　growth　of　reverted　austenite,　which　eventually　linked　to　form　a　net-like　structure　after　prolonged　aging.　The　net-like　austenite　in　the　direct-aged　samples　exhibited　low　thermal　stability　and　result　in　brittle　fracture　upon　impact　at　the　temperature　of　liquid　nitrogen　(-196　degrees　C).　Net-like　austenite　and　abundant　lath　austenite　in　the　cell　interior　were　found　in　the　low-temperature　solution-treated　samples,　which　exhibited　well-matched　strength,　toughness,　and　annealing　temperature.　Prior　homogenization　eliminated　the　microsegregation-induced　net-like　austenite.　The　measured　mechanical　properties　indicate　that　the　segregation-induced　net-like　austenite　failed　to　benefit　both　the　strength　and　toughness　of　the　studied　steel.