The main aim is to develop a sensitive method to detect trace protein in Chinese Materia Medica injections.A sample of 1μL was dotted on a PVDF membrane, and the membrane was washed with methanol to remove the color of the dot.Then,the membrane was stained with 025% Coomassie Brilliant Blue solution for at least 30 sec. After the stained membrane was washed with a mixed solution with methanol-water-acetic acid (45∶45∶1) to lower the background,a blot containing trace protein would appear.The color intensity of the blot was related to the protein content.This method was able to detect protein (＞12μg/mL) in 1μL sample,with high sensitivity and few interferences.Compared with the method of sulfosalicylic precipitation adopted by China Pharmacopoeia of 2010 edition,this method is more feasible.Also,the method is helpful to control protein content in Chinese Materia Medica injections.