The disciplinary characteristics of primary school science determine the importance of effective use of teaching aids in experimental exploration to improve teaching quality. The use of teaching aids can help students understand primary school science knowledge more intuitively. The experiment of light propagation is an important experiment in primary school science teaching, but the teaching effect based on the experimental teaching aids provided in the textbooks is not good. Only by innovating and improving the teaching aids can the teaching effect be improved. This article explores the method of improving the experimental device for light propagation along a straight line. By analyzing the specific content of the textbook, innovative improvements are made to the teaching aids from the aspects of materials, structure, etc., in order to facilitate the observation and summary of the law of light propagation along a straight line. It is expected to improve the teaching quality of light propagation along a straight line.