A　mathematical　model　was　developed　to　investigate　the　one-dimensional　transonic　flow　of　two-component　gas　mixture　with　spontaneous　condensation.　With　the　model　a　numerical　simulation　was　performed　for　the　two-component　condensable　gas　mixture　to　obtain　the　liquid　parameter　distribution　along　the　separator,　which　agreed　with　the　experimental　data　from　literatures.　The　model　was　extend　to　the　simulation　of　more　complicated　supersonic　separator　to　calculate　the　flow　parameters　and　their　distributions　of　two-component　condensable　gas　mixture,　which　revealed　the　change　rules　of　main　flow　parameters　in　one-dimensional　supersonic　separator.