In several types of research, analysis about mathematical reflective thinking skills viewed based on one independent variable as treatment given. The purpose of the research was to analyze the mathematical reflective thinking skills not only based on learning model but also viewed based on mathematical priorknowledge. The research was conducted at one of state junior high schools in Tangerang Selatan on the academic year 2017. The sample was taken through cluster random sampling technique as many as two classes with the total amount about 72 students. As a treatment, ill-structure problem-solving learning model implemented on experimental class and conventional learning models implemented on control class. Mathematical prior-knowledge was distinguished into three levels: low, middle, and high. Mathematical reflective thinking skills viewed based on three indicators: identifying a problem situation, predicting a solution, and evaluating the situation. Two Way Analysis of Varian has used to analyze the data with the level of significance about 0.05. The results showed that: 1) there was an effect of learning model towards students mathematical reflective thinking skills overall, 2) there was an effect of mathematical prior-knowledge towards students mathematical reflective thinking skills overall, and 3) there was interactional effect between learning model and mathematical prior-knowledge towards students mathematical reflective thinking skills. In general, the results showed that ill-structured problem-solving learning model contribute to students mathematical reflective thinking skills with a high and middle level of prior-knowledge.