A large of scaled development ongoing in industrial and infrastructure sectors in Indonesia. The government has designated a number of those projects to become the national strategic project. Some of the projects in the oil & gas industry include in the national strategic projects are categorized as megaprojects due to the cost of projects more than $ 1 billion. The scheme of projects is Engineering, Procurement, Construction and Commissioning (EPCC) or turnkey projects. Megaproject performance is considered disappointing due to almost of megaproject found will be over budget, delay and under quality. This performance is due to the complexity and uncertainty in megaprojects. Megaprojects delay will become a problem for contractors, project owners, and the government. There are indications of problems related to the schedule, quality, and cost of the project in ongoing mega projects in Indonesia. This research was led to analyze critical success factors during the engineering, procurement, construction, and commissioning phase of megaprojects in Indonesia, by a literature review and developing questionnaire to people who involve during the execution of megaprojects as project owners and contractors. The results found that the financial aspects category is the most important category apart from other categories such as unexpected events and commissioning related factors.