Abstract: Silica gel G TLC plate with n-butanol—acetic acid-water(4:1:1) as developing solvent was used. Isoprenaline hydrochloride and guaiphenesin, the chief components of isoprenaline hydrochloride aerosol, and its impurities contaminated from the pocking viols were separated and identified. The modified sulphuric acid formol reagent was employed as coloring agent of guaiphenesin. The determination of two components iust mentioned above were performed under UV and visible light. The average recovery Of isoprenaline hydrochloride was 100.0 ±3.6% and that of guaiphenesin was 99.3±2.7%(n=7)