Critical thinking skills have an impact on mental activities such as problem solving, decision making, hypothesis analysis, and scientific research. One way to improve critical thinking skills is through the application of learning models, such as Problem Based Learning (PBL) model. This study aims to determine the effect of Problem Based Learning model on junior high school students' mathematics critical thinking skills as a whole and in terms of grade level. Based on the meta-analysis conducted on 38 scientific publication articles show that Problem Based Learning model has a significant positive effect in improving the overall critical thinking skills of junior high school students in mathematics. The analysis also showed that the effect of Problem Based Learning model varied depending on the grade level, with grade IX having the most significant effect. Therefore, it can be concluded that Problem Based Learning has a positive impact on junior high school students' mathematics critical thinking skills.