Abstract: In the physical optics, we promote learning-centered teaching mode, and create a three-tiered progressive teaching design of “problem-oriented interactive classroom, immersive inquiry program, research-oriented project design,” and a five-ring constructive teaching model of “phenomenon-problem-theory-method-capability.” As a common data storage medium in daily life, the optical disc is also a reflective diffraction grating, with obvious grating diffraction phenomenon and easy to observe. In this paper, we take the project-based experiment on how to measure the laser wavelength and the track spacing of optical discs using diffraction gratings, as an example, to explore the teaching innovation practice of research-oriented project design in our courses. The proposed experimental method is simply designed with strong repeatability. It combines the grating diffraction theory with the actual diffraction phenomenon organically, which is helpful for deepening the understanding of the Fraunhofer multiple-slit diffraction effect.