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. KEY WORDS algorithms and computation theories, membership query, partial order, greedy algorithm 