Students still have difficulty in understanding the mathematics concepts in improving mathematical critical thinking skills, so there is a need for learning innovation by applying project based learning model. The purpose of this study was to find out the responses and learning outcomes of students with the application of project based learning model in improving creative and mathematical thinking skills in geometry courses of plane figure and polyhedra. This study was an action research. The subjects in this study were fourth semester students of the Mathematics Education Study Program, FKIP Universitas PGRI Mahadewa Indonesia for the academic year 2022/2023. The object of this research was the study and understanding of geometry courses of plane figure and polyhedra with the project based learning model. Two cycles were done in this study and each cycle went through four stages of activity namely: (1) planning, (2) action, (3) observation, and (4) evaluation and reflection. The results showed that there was an increase in each cycle, the score at the initial reflection was 63.0, in the first cycle it became 71.0, and in the second cycle it increased to 77.0. Classical completeness increased from 30.0% in pre-cycle became 60.0% in cycle I, and 90.0% in the cycle II. The results of observations towards student responses in the first cycle were 70.9 and in the second cycle were 79.7. Thus it can be concluded that (1) the application of Project based learning model can improve student learning outcomes, (2) there is a positive response to the application of the Project based learning model in improving learning outcomes in geometry courses of plane figure and polyhedra.