Problem-based learning is a student-centered pedagogy, in which students collaboratively solve complex and practices problems. Stage identify problem that are important to well-organized problem-based learning method. In this article, the authors distinguish two types of problems and problembased learning towards ill-structured problems. Those are the issues that are not clear, are not identify the correct answer, there are many solutions with the large amount of information. Methods for the identification ill-structured problems is based on the central principles and concepts. From the central principle and concepts built into problems or finding the existence of them in practice or by building elements opposed.