The ability of students to solve problems is one of the benchmarks for the success of student learning. The increasing ability of students to be able to solve problems in learning is largely determined by the thinking skills they have. One of them is critical thinking skills. However, in reality, the problem solving skills of students at SMAN 1 Tapaktuan are still relatively low. The purpose of this study was to determine whether the application of the Problem Based Learning model can improve students' problem solving skills on dynamic fluid material at SMAN 1 Tapaktuan and to determine the improvement of students' problem solving skills in terms of critical thinking skills on dynamic fluid material at SMAN 1 Tapaktuan by using the Problem Based Learning (PBL) learning model. The type of research used in this study is a quantitative approach with a Quasi Experimental Design method. The selected shape is Non equivalent Control Group Design. The instrument used in this research is a test of problem solving skills and a test of critical thinking skills. The results showed that the implementation of the Problem Based Learning model could improve the problem solving skills of students at SMAN 1 Tapaktuan. The improvement of problem solving skills in terms of students' critical thinking skills with the application of the Problem Based Learning (PBL) model shows that students who have high critical thinking skills, increased problem solving skills are in the high category.