It is a controversial issue that magnetism is an interesting topic for children but also the concept is too abstract for the preschoolers. In this study, an action research is conducted that examines whether the designed intervention program based on STEM can be beneficial for 5-6 years old children to learn more about the specific features of the magnets. The program consists of several activities including reading story, playing a tablet game and designing a product from different shaped magnets. Findings underline the importance of STEM activities, as an interdisciplined approach, can foster the children to engage more actively in learning, inquiring, designing and reflecting processes. Besides, this study confirms the claim that preschool children are capable of developing conceptual understanding in 'magnetism'.