This study investigated and analyzed feasibility analysis case studies, carried out by contractor of EPC LSTK projects in the planning stage to suggest the strategies to solve problems for project improvement. For this, five feasibility analysis case studies of gulf cooperation council (GCC) countries were reviewed and investigated. The results can be summarized as follows: 1) Those factors needed to be analyzed, including cost increase, project delay, quality decrease were insufficiently considered when assessing feasibility. 2) And improvement strategies for three problems mentioned above were suggested based on findings in feasibility analysis. 3) Lastly the process of the project feasibility analysis that can be applied to overseas plant construction project was suggested step by step.