The purpose of this study is to analysis of risk factors in engineering, procurement, and construction phases for overseas plant project. The possible risk factors were carried out and classified into the three phases after a careful review of previous research and related papers. These risk factors were examined to evaluate its significance and effect on cost and schedule through AHP method after interviews with professionals. The results from the above described procedure are summarized as follows. 1) A total number of 32 risk factors were carried out. 2) The risk factors with the highest significance, the most effect on cost and schedule were derived for each phase as follows. In engineering phase, the frequent modification in design (E-08) had the highest significance; the errors in detail design (E-03) had the most effect on its cost; the errors in basic design (E-02) had the most effect on its schedule. For procurement phase, the material procurement delays (P-05), the price changes in main equipment (P-08), and the main equipment delivery delays were the factors recognized as the above. For construction phase, the subcontractors with low technical skills (C-08), the modifications in design (C-01), and the subcontractors with low technical skills (C-08) were the factors recognized as the above.