Fe-10%Ni alloys were synthesized in a high energy horizontal rotary ball mill from pure element Fe and Ni powders. Phase constitution, shape and thermal stability of the milled powders were characterized using X-ray diffractometry (XRD), scanning electron microscopy (SEM) and differential thermal analysis (DTA), respectively. And microstructure and properties of bulks prepared by hot-press sintering with milled powders as starting materials were analyzed and tested. Results indicate that under the condition of a milling speed of 400 r/min and a ball-to-powder mass ratio of 20:1, Ni fully solubilizes in Fe, which forms a supersaturate solid solution of Fe(Ni) with a body-centered cubic structure. Particles of the powder milled up to 16 h are more homogeneous and finer than those of the powder milled for 8 h, but phase of the powder is still Fe(Ni) solid solution. The alloy powder milled for 16 h were annealed in the temperature range between 500 and 800 oC. It is found that structure of the powder after annealing is stable and no phase transformation occurs in the powder. Phase of the powder is still Fe(Ni) solid solution. When the alloy powders milled for 16 h were treated by hot pressed sintering at 950 oC, a little Fe(Ni) solid solution with a face-centered cubic structure is found in the bulks. If the bulks that previously were treated by hot-press sintering at 950 oC and cooled to room temperature were subsequently sintered at 970 oC again, the phase of the powders completely transforms to Fe(Ni) solid solution with a face-centered cubic structure. However, the strength and ductility of bulks treated by hot-press sintering at 950 oC are superior to those of bulks by subsequent sintering at 970 oC, because oxide and holes are produced in resintered bulks without pressure.