It is well known that Ni3Si intermetallic compounds have an excellent corrosion resistance in H2SO4 solution. However, practical production has been difficult because of poor ductility caused by very brittle phase which is liable to be formed. Therefore, the process conditions involving a mechanical alloying(MA) technique were investigated in order to obtain final products composed of Ni3Si stoichiometric single phase compo-und by suppressing the formation of brittle phase. In this paper, fine Ni-Si composite powders which have been prepared by the MA method were hot extruded, thereafter β phase - Ni3Si consolidates were obtained by a specific heat treatment. The influence of compositions, MA conditions and heat treatment conditions for obtaining the β single phase - Ni3Si intermetallic compounds were investigated. It was confirmed that consolidates of Ni3Si intermetallic compounds with almost single phase(β phase) can be obtained under the following conditions: composition of 13.1 mass%Si and 86.9 mass%Ni, MA(B/P=16) for 346ks, extrusion at 1223K and heat treatment at 1223K for 18ks.