Abstract: Objective: To establish a thin layer chromatography (TLC) identification method for Phellodendri Chinensis Cortex,Borneolum Syntheticum and Rhei Radix et Rhizoma in Modified Shuangbai Gel Paster, investigate their quality stability, and preliminarily evaluate the drug safety of Modified Shuangbai Gel Plaster. Methods:Phellodendri Chinensis Cortex,Borneolum Syntheticum and Rhei Radix et Rhizoma in the prescription of Modified Shuangbai Gel Paster were identified by TLC, and its stability was investigated by accelerated test,long-term test and influence factor test. The skin irritation test was conducted many times with New Zealand rabbits as the model,and the active skin allergy test and Buehler test were conducted with Hartley guinea pigs as the model to observe the skin irritation and sensitization of gel plaster. Results: The chromatographic spots in TLC were clear and characteristic, and the negative control had no interference. The three batches of products have good stability in the long- term test and accelerated test. The Modified Shuangbai Gel Paster has no irritation to the skin of New Zealand rabbits and no allergy to the skin of guinea pigs. Conclusion:The established TLC can be used as the quality control method for Modified Shuangbai Gel Paster, and Modified Shuangbai Gel Paster is a relatively safe new external preparation with stable and controllable quality.