Abstract: Protein content determination is an important technique of biological experiments.There are many methods to determine protein content,and the most common method used in laboratories is the Coomassie brilliant blue method.Although the principles and experimental steps of this method are simple,there are many technical details related to the teaching materials and literature that are not introduced in the experimental process.Ignoring any the details can cause the failure of the experiment.In this paper,the determination of soluble protein content in plants was taken as an example,the Coomassie brilliant blue method was introduced to determine the principle of protein content,reagents,instruments and equipment,and operating procedures.The highlighted details that should be paid more attention during the experimental operation are mainly introduced,and the experience accumulated in laboratory is shared,so as to improve the students’ operational skills and the success rate of experiments.