The main purpose of this study is conclude the critical success factors on implementing Enterprise resource planning (ERP) system through the channel of issuing questionnaire to P company, which has successfully implemented ERP system in Taiwan. The result of this study showed that there were three major factors, indeed intention and fully support from management level, the integrated system function, and solid training program, are most helpful for enterprises successfully implementing ERP systems. By the PCA (Principle components analysis) process, two critical factors are suggested (1)sound preparation before system implementation, and (2) the characteristics of the ERP system. The two factors are important due to their influences on system implementation with explanation is 65%, if adding another factors will increase the variation ability to 85%. Evaluating the effect of implementing ERP on the benefit is rather difficult at this moment since corresponding benchmark are not built up yet. This study proposes suggestions on how to successfully implement ERP systems, which may be provided as references to the enterprises.