Abstract: In the traditional “acetone iodination” experiment, there are problems such as corrosion, irritation caused by HCl volatilization, and inconsistent temperature or time between the spectrophotometric test and the actual reaction process. These problems are inevitably encountered and have not been effectively addressed. With a focus on these problems, the improved experiment presented a colorimetric analysis system based on a smartphone and new glass reactor; the test method was also proposed. The improved experiment avoids instrument corrosion, human body stimulation caused by HCl, improves the accuracy of the experimental data, and is helpful for students to gain theoretical and experimental expertise on the Lambert-Beer law and its offset phenomenon. In addition, since a spectrophotometer is not required, the improved experiment is easier to popularize and more interesting. It also provides a new strategy for online experimental teaching under difficult conditions such as the epidemic.