Enterprise resource planning system is a software package with extensive application which integrates all organizational functions in a single system. To implement an ERP project in an organization successfully, selecting an appropriate system considering effective factors is necessary. The purpose of this study is to identify effective factors in selecting ERP. This study has used expert choice to investigate content validity and Cronbach Alpha (0.79) to consider reliability of the research questionnaire. Seven factors are identified by exploratory factor analysis including general specifications, implementation costs, price, vendor, functional capabilities, project management and software quality capabilities. Finally, some suggestions to choose an appropriate ERP system are presented.