This research aims to describe the improvement of students' ability to solve HOTS-based mathematics problems with the theory of problem-solving from Polya. This research used classroom action research. Data collection techniques use interviews, tests, observations, documentation, and field notes. Data analysis techniques use a flow method consisting of data reduction, data presentation, and data verification. The results showed a classical improvement in students' ability to solve HOTS-based math problems, it can be seen that each indicator reaches a targeted percentage of ≥ 60%, starting from before the action to the second cycle of action.Thus, the conclusions of this research show that Polya's problem-solving theory can improve students' ability to solve HOTS-based math problems.