工程變更是產品在量產週期內無可避免的主要活動，一般而言工程變更是針對已經正式進入量產的產品所構成的零件(BOM)進行的變更，其變更囊括零件的材料、特性、供應商、原料、尺寸、製程、包裝、設計…等方面的改變，皆可稱為工程變更。 儘管我們都知道工程變更的重要性，但並非所有公司都有完整的流程去控管，一個有效的管理方法對所有工程變更的可靠度測試進行管理、及時監控甚至進一步分析是非常重要的，若公司內部無適當的管理系統去監控，導致流程不透明，出現任何品質問題時僅能被動處理，且工程簽核時間拉長導致重要變更無法即時導入。這將會嚴重影響產品的可靠度及客戶觀感。 本論文旨要透過DMAIC手法，以台灣Z公司為個案探討產品量產期設計品質管理部門對硬體工程變更 (Engineering change) 的可靠度測試計畫擬定與系統式的管理，我們期望改善工程變更的測試計畫管理方式，確保所有問題都有完整的改善迴圈並透過精實六個標準差的各種手法進行分析並加以改善審核流程，研擬改善對策並透過系統簽核時間比對並證明其結果。 ;Engineering change is the unavoidable activity when product during the mass production cycle. The purpose of EC is when change to the part (BOM) made of the product that has officially entered mass production. The change includes the material, characteristics, Vender change, raw materials, dimensions, manufacturing processes, packaging, design, etc. can all be called engineering changes. We all know the importance of engineering changes, not all companies have complete processes to control and manage. It is very important that an effective management method manages, monitors and even analyzes the reliability test of all engineering changes. There is no proper management system in the company to monitor, resulting in opaque processes. Any quality problems can only be handled passively, and prolonged project signing time leads to important changes that cannot be imported immediately. This will seriously affect product reliability and customer perception. The purpose of this thesis is to use the DMAIC method to take Taiwan Z company as a case to discuss the design of the quality change department ’s reliability test plan for the hardware engineering change and the systematic management. Test plan management method to ensure that all issues have a complete improvement loop and analyze and improve the review process through a variety of methods to refine the six standard deviations, develop improvement countermeasures and compare and prove through the system signing time the result.