This study aims to examine the effectiveness of STEM learning with the PjBL model on creativity and conceptual understanding of elementary school students. The Research design used in this study is a quasi experimental design. The research subjects were 60 elementary school students who were divided into 2 homogeneous classes, consisting 30 students in the experimental class and 30 students in the experimental class. Students in the control class were taught by conventional methods and in the experimental class were taught by STEM learning with the PjBL model. Creativity data was taken with a creativity test instrument with a reliability of 0.84. Data analysis was carried out using ANCOVA followed by the effect size test. The results show that there are differences in students' creativity and understanding of concepts were taught by STEM learning with PjBL and conventional models. The effectiveness of STEM learning with the PjBL model on creativity and understanding of science concepts for elementary school students is significant in large categories