The influence of solution annealing on the microstructure and mechanical properties of high nitrogen Fe-Cr-Mn-Mo-N austenitic stainless steels prepared by MIM was investigated. The results show that the solution treatment can improve the microstructure and properties of the stainless steels significantly. The sintered specimens before solution annealing consist of γ-austenite and embrittling intergranular Cr2N precipitates, showing a low mechanical property. After solid solution annealing, the specimens reveal a fully austenitic structure without any intergranular nitrides, whose tensile properties are much higher than those without solution annealing, which is attributed to the elimination of the nitride precipitation along the grain boundaries and the greater amount of nitrogen retained in solid solution. A mixed mode of intergranular and dimple fracture happen to the specimens before solid solution treatment, while a completely tough fracture of dimple happen to those after solid solution treatment.