Abstract: Urine sample (2.5 mL) from healthy person was taken and added with 4.5 mL of HClO₄ solution (1+9). The mixture was vortically oscillated for 30 min. After centrifuging, the supernatant was taken and its acidity was adjusted to 4.5 with 100 g·L^-1 NaOH solution. The contents of adenine, guanine, cytosine and thymine in the supernatant were determined by DPV with self-prepared carbon paste electrode (by mixing raphite powder and silicon oil Ⅲ with mass ratio of 5 to 1) as working electrode, and 0.1 mol·L^-1 acetate buffer solution of pH 4.5 was used as electrolyte. As shown by the results, linear relationships between values of peak current and mass concentration of the 4 alkaloids were found in definite ranges, with detection limits (3S/N) of 0.090, 0.050, 17, 2.8 μmol·L^-1 respectively. Test for recovery was made by standard addition method, giving results of recovery in the range of 92.5%-109%, and RSDs (n=5) ranged from 0.90% to 4.3%.