在模擬免疫系統的主組織相容復雜性的基礎上，結合模糊邏輯與擴展陰性選擇算法提出了一個基于免疫系統主組織相容復雜性的模糊邏輯綜合決策算法，并用該算法構建了一個實際的基于網絡的入侵檢測系統。該算法應用高效的擴展陰性選擇算法作出第一次網絡流量檢測，當網絡數據異常特征明顯時，能直接檢測出入侵。若其不能準確地識別待分析數據，則利用具有檢測結果準確優勢的規則匹配算法作出二次檢測，最后結合兩次檢測結論用模糊邏輯決策模型做出綜合決策。A novel algorithm based on the simulation of the major histocompatibility complex feature of human immune system is proposed. The extended negative selection algorithm makes the first decision to decide whether the network traffic is intrusion. Another algorithm, rule match-based alglrithm, makes the second decision while the first decision failed to identify the intrusion. The proposed algorithm, called major histocompatibility complex feature-based synthetic fuzzy decision-making algorithm, composes the first decision and the second decision to make a synthetic fuzzy decision by taking advantage of fuzzy logic.