The work aims to study the compatibility of commonly used preservative system components in cosmetic contents with nitrile rubber caps to provide theoretical support for the subsequent application of nitrile rubber in cosmetic dropper bottles. Experiments were conducted to analyze the chemical composition of the compatibility reaction solution using FTIR, NMR, GC-MS, XRF, MS, ICP and other instruments. The results indicated that, for glass dropper bottles of nitrile rubber caps, the plasticizer used for cap molding would precipitate from the cosmetic solution or react with alcohol at high temperature, and the vulcanizing agent in the cap would also migrate at high temperature, making the solution yellow. In conclusion, the plasticizer components in nitrile rubber are incompatible with the alcohols (such as butylene glycol, propylene glycol, pentylene glycol) in cosmetics.