Abstract: According to some research achievements, a comprehensive experiment containing the synthesis of formaldehyde modified polyethyleneimine and determination of fluorescence quantum yield was designed. The formaldehyde modified polyethyleneimine was obtained by using polyethyleneimine and formaldehyde as raw materials and refluxing at 90℃ for 1 hour in a water bath. Using quinine sulfate as a reference, the relative quantum yield of the fluorescent material was tested by the “comparative method” and compared with the “one-point method”. Through the development of this experimental project, students are expected to master the structure and principles of several spectroscopic instruments such as ultraviolet-visible spectrophotometer, fluorescence spectrophotometer and infrared spectrophotometer, master the basic operation skills and applications of these devices, and master the fluorescence quantum efficiency. Test principles and test methods to improve students' ability to analyze problems and solve practical problems.