Results: The quantitative test has been developed using HPLC with chromatographic conditions: column C18, the mobile phase consists of 1.21 g sodium 1-heptansulfonat in 600 ml water: 400 ml methanol and 1 ml phosphoric acid, adjust to pH = 3; detected by PDA detector at 210 nm.%); flow rate: 1ml / minute; injected sample volume: 20 µl. The extraction method of clonidine from the patches used 10 ml cloroform and 10 ml and HCl 0.003% (cloroform was used to destroy the adhesive layer, HCl 0.003% was used to change Clonidine base into Clonidine hydrochloride), the acid layer was taken to assay.