Nowadays educational robots have begun to walk into campuses and households, changing the traditional way of teaching and learning. There are many physical or virtual robot education platforms on the market now, whose perfect systems and mature hardware or software not only reduced the difficulty of learning but also limited the creativity of users. Taking this as a starting point, this paper proposed a method of designing a simple robotic arm system, including motion analysis and control algorithm design, and verified it through an example. Generally, the method proposed in this paper can help robot enthusiasts, especially beginners, to explore and practice the process of building robots just with simple materials.