There are different properties among high-alkaline detergents from different companies or different batches, which have a great impact on lubricant performance. This article analyzes the composition and structures of three high-alkaline detergents. The additives are extracted and analyzed by rubber membrane dialysis, infrared spectroscopy, and nuclear magnetic resonance, etc. The results show that the detergent with excellent performance, S206(I), has the advantages of effective content, average molecular weight, and dispersion degree. Several compositions, such as stearic acid, can be found in S206(II). And S206(III), the detergent with inferior performance, contains the most impurities.