Abstract: OBJECTIVE To establish a method for the simultaneous determination of the active part contents (neohesperidin and naringin) in rat urine and feces. To study the urine drug excretion pharmacokinetics and characteristics after the extract was given to the rats orally. METHODS UPLC-MS/MS was used to establish a quantitative analysis method for the active parts(neohesperidin and naringin) in rat urine and feces. The excretion rates of neohesperidin and naringin in urine and feces at different time points were calculated after the extract was given orally. The elimination half-lives and elimination rate constants in urine were calculated by using sigma minus method. The urine drug excretion pharmacokinetics and characteristics was evaluated after the extract given to the rats orally. RESULTS The UPLC-MS/MS quantitative analysis method established had good specialization, standard curve and linear range. The accuracy, precision, and quantitative lower limit of the method all conformed to relevant standards. The method was able to quantitatively determine the active parts in rat urine and feces. The average cumulative excretion rates for neohesperidin and naringin in rat urine were (1.76±0.76)‰ and (1.39±0.57)‰ respectively 72 h after oral administration, and the values in rat feces were (52.45±6.30)% and (51.57±4.80)% respectively. The excretion amount for neohesperidin and naringin in urine and feces reached the peak at 24-36 h and 4-8 h after oral administration respectively. The active parts were still detectable in urine 72 h after oral administration, but the cumulative excretion rates in feces reached the plateau at 24 h. By using sigma minus method, the elimination rate constants for neohesperidin was calculated to be (0.080±0.021)·h^-1, and the elimination half-life was (9.41±3.22)h. The values for naringin were (0.077±0.017)·h^-1 and (9.51±2.97)h respectively. The difference in the kinetic parameters between the two active parts had no statistical significance. CONCLUSION After oral administration, the original compounds of the active parts are quickly excreted in feces. Feces excretion is the main excretion way of the active parts. There are no significant difference in the excretion characteristics of the two active parts in urine.