This research is motivated by integrated thematic learning that has not been well implemented, is still in the process of improving. This causes the integrated thematic learning process to be carried out to the maximum. The purpose of this study, to improve the integrated thematic learning process using the Problem Based Learning model. This type of research is classroom action research using qualitative and quantitative approaches. This research was conducted in the second semester of the 2018/2019 academic year. The results of the study showed an increase in: (1) the learning plan, namely cycle I obtained a percentage of 85,71% (good), cycle II obtained a percentage of 96,42% (Very Good). (2) the implementation of learning cycle I obtained a percentage of 85,71% (good), cycle II obtained a percentage of 96,42% (Very Good). It can be concluded that the Problem Based Learning model can improve the integrated thematic learning process in elementary schools.