OBJECTIVE： To prepare Pramipexole dihydrochloride sustained-release pellets capsules and to establish a method for the determination of related substances. METHODS： Drug loaded core was prepared by fluid bed air suspension coating method， and pramipexole dihydrochloride pellets were prepared using Surelease® as coating materials and put into capsules. HPLC method was used to determine related substance in sustained-release pellets； the determination was performed on Capcell PAK MG-Ⅱ C18 column （150 mm×4.6 mm， 5 μm） with mobile phase A consisted of ammonium formate buffer solution （pH 5.0） and mobile phase B consisted of methanol for gradient elution at flow rate of 1.0 ml/min； diode array detector was used with detection wavelength of 240， 262， 326 nm and injection volume of 80 μl. RESULTS： Pramipexole dihydrochloride and 7 kinds of related substances were separated by the established HPLC conditions. The blank excipient did not interfere with the assay of the related substances. The linear ranges of 7 related substances were 0.2-2 μg/ml （r＞0.999 0）； the limit of detection ranged 0.5-1.8 ng， and the limit of quantitation ranged 1.7-5.9 ng； average recovery ranged 98.93％-102.0％ （RSD were 1.90％-0.24％，n＝9）. RSD of precision and stability test were all lower than 1.0％ （n＝5）. Only one related substance was found in prepared Pramipexole dihydrochloride pellets capsules. CONCLUSIONS： Pramipexole dihydrochloride pellets capsules are prepared successfully. Established HPLC method can be used for the determination of its related substances.