Measuring the focal length of a thin optical lens is a classical primary physics experiment，while traditional teaching strategy has shown incapacity to duplicate the experimental beam pathways，component locations and image quality．Seelight software is applied in simulating the experimental process of measuring the focal length of a concave lens，especially in demonstrating the link between lens locations and image characteristics simultaneously． Combined with on-hand operation，the software simulation can provide the students with comprehensive understanding of the experimental architecture and theory，and improve their learning efficiency．