Abstract: OBJECTIVE To develop a method for determing the content of related substances of hydrochloric acid pramipexol. METHODS HPLC was used to establish the linear equation of pramipexole hydrochloride and its impurity A, B, C and E. The slope of linear equation was used to determine the correction factor of impurity A, B, C and E, and the validation of the analytical method was determined. RESULTS The correction factors of pramipexole hydrochloride impurity A, B, C and E were 0.642, 0.999, 0.796 and 0.642, and the relative retention time was 0.703, 1.512, 1.733, 1.512. Impurity A, B and E were not detected in 3 batches of samples, and the content of impurity C was respectively 0.013%, 0.013% and 0.012%. CONCLUSIONS The correction factor method is viable to determine the content of related substances of pramipexole hydrochloride dihydrate.