Abstract: OBJECTIVE To establish an HPLC-CAD method for determination of the content and the related substances of hydroxycarbamide capsules. METHODS The determination was carried out on a Phenomenex Luna^® NH₂(250 mm×4.6 mm, 10 μm, 100Ǻ) column at 40℃, with acetonitrile-water(82:18) as mobile phase at a flow rate of 1.0 mL·min^-1. The detector of charged aerosol detection was applied with a high nebulization temperature at 50℃, the injection volume was 10 μL. RESULTS Under the selected chromatographic conditions, related substances were completely separated from the principal component. The content of hydroxycarbamide capsules was calculated by the external standard method of the reference substance, and the content of carbamide was calculated by the self-control method of the main component. Hydroxycarbamide and carbamide showed a good linear relationship with the peak area in the concentration range of 0.304 8-1.270 0 mg·mL^-1(r=0.999 8) and 0.241 1-1.004 6 mg·mL^-1(r=1.000 0), respectively. The detection limits and quantitation limits of carbamide were 2.82 ng and 8.46 ng, respectively. CONCLUSION The method is simple, specific and reliable, and can be used for the determination of the content of hydroxycarbamide capsules and related substances.