Objective To study the stability of glacial acetic acid paint and to characterize its related substance.Methods Neutralization micrometric method was used to determine acetic acid of the medicine in different solvents and by different storage method.The related substance was determined by GC.Results During storage,the content of acetic acid in the preparation decreased quickly while that of ethyl acetate increased.Acetic acid of the paint in the fridge decreased mores lowly than at room temperature.However,acetic acid in glacial acetic acid water solution was very stable.The related substance was ethyl acetate,the side product of acetic acid and ethanol.Conclusion The glacial acetic acid paint is unstable at room temperature and should be stored in the fridge.