The general objective of our study is to provide managers with an understanding of business process optimization and its role in a modern organization. This study will focus on two (2) main areas: In the first part, we will address the conceptual and theoretical framework of business process optimization, starting with theories on accounting organization, followed by a presentation of the conceptual framework of business processes; In the second part, we will diagnose the business processes of the Accounting Department, followed by the presentation of an architecture for reorganizing the bank's Accounting Department. We will then make a few recommendations on the practice of business process optimization at CNCE, before concluding our study.