Optimization of business processes is an important thing that must be solved efficiently. However, many small medium enterprises (SME) in the food sector industry are not completely aware of the potential for savings presented by technologies and digital business tools to manage data transactions. Problems that arise in the SMEs’ accounting information system and invoicing are when they do not implement the technology to integrate the invoice data from one to another division. On the other side of problems, paper invoices have been causing high costs and slow processing times. To overcome it, SMEs need a system that effectively resolves the high price of invoice processing operations. One of the best solutions is to implement open source ERP systems. Considering the problem, OpenERP was chosen by this research as open source ERP software that can help SMEs to improve the integrated invoice system and the accounting cycle automation based on Quickstart methodology.