OBJECTIVE： To establish a method for the content determination of AV45 （the labeled precursor of PET agent for Aβ plaques） and its related substances. METHODS： HPLC method was performed on the column of Inertsil C18 with mobile phase of 50 mmol/L Disodium hydrogen phosphate solution - acetonitrile （containing 0.01％ triethylamine） （15 ∶ 85，V/V） at a flow rate of 1.0 ml/min， the detection wavelength was 325 nm， and column temperature was 30 ℃， and volume injection was 20 μl. RESULTS： The AV45 and reaction intermediate as well as individual impurity peaks were well separated； the linear range was 200-1 000 μg/ml for AV45 （r＝0.999 2） and 20-100 μg/ml for intermediate （r＝0.999 6）； the detection limit and quantification limit of reaction intermediate AV45 were 0.1 ng and 0.5 ng， respectively； RSDs of precision， stability and reproducibility tests were lower than 0.5％； recovery of AV45 was 98.93％-101.58％（RSD＝0.69％，n＝9）. CONCLUSIONS： The method is simple and accurate with high specificity and good reproducibility， and suitable for content determination of AV45（the labeled precursor of PET agent for Aβ plaques） and its related substances.