Detection method of fasudil hydrochloride-related substance

The invention relates to a method for detecting an impurity dipolymer in fasudil hydrochloride with high performance liquid chromatography. According to the high performance liquid chromatography disclosed by the invention, fasudil hydrochloride can be well separated from a byproduct dipolymer introduced in a synthesis process effectively, the detection level of a fasudil hydrochloride raw material is raised, and quality control of fasudil hydrochloride is enhanced; and the method has high specificity and high accuracy, and is easy and convenient to operate.