Abstract: Two experiments were designed to determine the effects of oral administration of Pu’er tea extracts on serum nicotine and cotinine concentrations in passive smoking mice. In the experiment 1, fifty ICR mice were assigned randomly to one of five treatments to receive cigarette smoking time 10, 20, 40, 60, or 80 min, observed the mice behaviors. The results showed that 60 min was prior in this experiment. In the experiment 2, one hundred and eighty ICR mice were assigned randomly to one of three treatments with 10 mice per group. The control group orally administered physiological saline, group I orally administered physiological saline and received cigarette smoking, and group II orally administered Pu’er tea extracts and received cigarette smoking. The mice serum was sampled on d 7, 14, 21, 28, 35, or 42, and the serum nicotine and cotinine concentrations were determined. The nicotine concentrations of group I and II were higher (P < 0.01) than those of the control during the period of the second experiment, and the nicotine concentrations of group II were lower than those of group I on d 14 (P = 0.01), 21 (P = 0.02), 28 (P < 0.01), 35 (P < 0.01), or 42 (P < 0.01). The cotinine concentrations were no significant difference between group I and II. The findings of this paper showed that oral administration of Pu’er tea extracts could reduce serum nicotine in passive smoking mice.