在生產系統中，製程常會發生異常狀況，管理者爲了確保品質穩定，會透過各種品質改善策略來達到穩定製程品質的目的。因爲不同品質改善策略，所須付出的品質成本與獲利關係非常複雜，故本研究在統計製程管制架構下，針對製程發生異常狀況，探討管理者採取不同品質改善策略所需付出的成本及預期獲利情況，以品質成本與效益之觀點，考慮產品可維修的情況下，建構品質與成本之利潤增額模型，找出使增額利潤最大化下之最佳品質改善策略。最後舉一數值範例，以驗證此模型之可行性，所獲得之具體結果，可作爲後續研究及實務應用之參考。

In production system, manufacturing process sometimes shift into abnormal situation. When the manufacturing process is out of control, managers applied all kinds of quality-improving strategies to improve their product qualities within the required specification and stable. Besides, different quality-improving strategies have very complex relationship between quality costs and revenue. So, under the frame of statistic process control and aiming at the abnormal situation of manufacturing process, we discuss what the cost be paid and how much revenue be earned by taking different quality-improving strategies. Under the consideration of the products is repairable and the viewpoint of quality cost and benefit, we can build a incremental profit model on quality and cost and search for the optimal quality-improving strategy to maximize the incremental profit. Furthermore, we also proposed a numerical example to illustrate the meaning of this research and the result, which could be used by the later researches and actual applications.