Nowadays, the majority of the companies and organizations all around the world are highly depend on the HR module of the ERP system as a tool for supporting the HR departments, making it flexible to access other departments’ specific employee data. The purpose of this paper is to conduct a comparison study of the HR modules’ of 3 major ERP systems SAP, Odoo, and Microsoft Dynamics AX, in order to provide a scientific approach for selection the best ERP solution by investigating all of the aspects of the HR module to the Missan Oil company in IRAQ.