Methodology is a body of knowledge that empower researchers to explain and analyze a phenomena through association between research paradigms and strategies (i.e., quantitative (quan), qualitative (qual), or mix- method). In recent decade, the proficient of mix-method have raised up own philosophical, methodological, analytical and practical foundations for conducting the mix-method designs. However, there exist many communications related to the more common definitions of mixed methods research, it is yet required to be specify the particular criteria in choosing mix-method design for educational researches. Therefore, this study intends to provide a process of critical decisions for selecting suitable mix- method design. In this respect, an archive study is conducted to provide an overview of the four common mixed-method designs including: “Triangulation”, “Embedded”, “Explanatory” and “Exploratory”. In addition, the strengths, the challenges of each design, and the ways applying them are discussed. Conclusively, to perform an effective mix-method, researchers have to make decision about timing, weighting, as well as mixing source of quatitative and qualitative. Meanwhile, they shoud be able to state their philosphy of selected design regarding to their required skills and competency as well as justify their validity of findings. We assert that these findings can assist junior educational researchers to inquire their objectives in a consistent manner.