Consider　the　problem　of　membership　query　for　a　given　partially　ordered　set.　We　devise　a　greedy　algorithm　Which　can　produce　near-optimal　search　strategies.　Rigorous　analysis　has　been　given,　which　shows　our　algorithm　can　have　fewer　comparisons　than　the　best　known　solution　by　at　least　a　factor　of　0.27　under　random　graph　model.　Experimental　results　have　also　been　given,　which　suggest　the　advantage　of　the　algorithm　under　other　models.