The aim of this study is to investigate the effects of 3D computer models on students' academic achievement and mental models about atomic models. Sample of the study was chosen from the Department of Primary Science Teacher Training of Kazim Karabekir Education Faculty of Ataturk University. In order to determine the effects of 3D computer models on students' academic achievement and mental models about atomic models AAT and MMIT was used. The reliability coefficient for AAT was found as 0,64. It was administered to 83 students (40 for EG and 43 for CG) and results evaluated by SPSS packet programme. After results it can be clearly said that 3D models are useful to improve students' academic achievement and their mental models.