The scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) were adopted to investigate precipitates in 46Fe-33Ni-15Cr and 50Fe-27Ni-20Cr valve alloys. The results show that 46Fe-33Ni-15Cr alloy contains γ", σ and MC phase after solution and aging, however 50Fe-27Ni-20Cr alloy contains γ", σ, MC and Laves phase. The γ" phase has two patterns, spherical and cellular in 46Fe-33Ni-15Cr alloy. But only one pattern of γ" phase spherical exists in 50Fe-27Ni-20Cr alloy, and its size is about 20nm~40nm,smaller than that in 46Fe-33Ni-15Cr alloy. The σ phase distributes in strip on the grain boundary in 46Fe-33Ni-15Cr alloy, but it precipitates in needle shape along the grain boundary in a certain orientation. Within 2000 hours aging under 700℃, the amount of σ phase in 46Fe-33Ni-15Cr increases more rapidly than that in 50Fe-27Ni-20Cr alloy with the increasing aging time.