This research was motivated by the low science learning outcomes of fourth-grade students in mis Darrul Qolam Kabupaten Bandung. Science learning should provide opportunities for students to be active in discovering learning concepts. Through the discovery learning model, students were directed to find their own learning concepts. For that, we need media that are effective, attractive, and easy to use. PhET Simulations (Physics Education Technology) is a virtual simulation media, which can provide a better understanding of science learning concepts. The purpose of this study was to determine the effect of using discovery learning models assisted by PhET Simulations on student learning outcomes. This study used a pre-experimental method with a one-group pretest-posttest design The research subjects were 28 fourth grade students of MIS Daarul Qolam Kabupaten Bandung. The data collection technique used a written test in the form of multiple choice questions.Based on the results of research and hypothesis testing using the t-test, the value of t calc 11.44 > t table 2.11, meaning that Ho is rejected, and the N- gain test results obtained a value of 0.62 (moderate criteria). Thus, it could be concluded that there was an effect of using discovery learning models assisted by PhET Simulations on student learning outcomes. The results of this study could be used as a suggestion and recommendation for further research, to develop the use of discovery learning models assisted by PhET Simulations for various aspects of learning outcomes that more complex, especially in science learning in elementary schools.