Enterprise Resource Planning (ERP) system is a strategic integrated solution based on information technology to response organization's needs for information. Implementing ERP system enables organizations to manage integrated data flow between processes and departments. The basis of ERP systems is production system. Significant advantages of using these systems in production industries lead to extension to other industries; particularly construction industry. It is necessary to attend unique properties of construction industry while developing construction ERP (CERP) systems. In addition, construction is a local industry; therefore the essential condition for the success of CERP systems is attention to principles, rules and properties of each country. Most systems used in Iranian construction companies are not integrated and ignore Business Process Re-engineering (BPR) principles. In this thesis, an appropriate ERP system for Iranian construction companies is designed. Since these systems have modular structure, it is necessary to identify modules and their subdivisions. The architecture of these modules should meet needs and transactions of all processes in a construction company. In this research, in order to recognize construction industry's processes, the performed filed study includes ten Iranian construction companies. In addition to field study, a process classification framework (APQC) and a standard project management method (PMBOK) are used. Finally, nine modules and subdivisions related to each of them are identified. These modules are ranked based on their role importance in achieving expected advantages of the system. In this part, Simple Weighted Average (SAW) method which is one of the multi criteria decision making (MCDM) methods is used. The proposed system is designed based on identified modules and their data flow. Object Process Methodology (OPM) which is one of ERP modeling methods, is used for designing the system. Object Process Diagram (OPD) is a tool in this methodology which makes modeling the system possible. One of the benefits of this model is to consider the structural, functional and dynamic features of system. There has been no research published about designing and modeling ERP systems for Iranian construction industry. By using the results of this research, construction companies could find their needs in information systems area clearly and systematically. Validity of this model is based on the knowledge, practices and needs of companies in field study area, APQC and PMBOK. Obviously, final success of this model could be evaluated by coding and implementing it in Iranian construction companies