EPC project is one of complex construction project types which differs from ordinary construction projects. It owns more frequent delayed occurrence than ordinary construction projects. EPC projects tends to be labor and knowledge intensive. Inputs and outputs at EPC project management involve various knowledge and intellectual creative activities. Thus, the EPC project management process is a knowledge management process. Knowledge Management System (KMS) aims to improve the quality of human resources in an organization by improving communication among all parts of the organization and increasing knowledge mastery by transferring knowledge. The application of KMS with a blockchain-based system is expected to be a solution for the needs of distributed knowledge transfer, high-speed transfer of knowledge and information, fast access to knowledge and high information security. This study uses the Tiwana model framework, and for organizational knowledge mapping uses the Zack KM model cycle, while the SECI model is used for knowledge formation. The quality of the resulting blockchain-based KMS platform is tested by using expert validation. The research result shows that blockchain-based KMS model can be well implemented with excellent validation so it becomes a solution to increase knowledge and to improve project time performance in EPC-X project.