Based on both the in vivo and in vitro way and the Marc 145 cell culture system, the effects of aqueous extracts from teas on porcine reproductive and respiratory syndrome (PRRS) was assessed regarding the cytopathic effect (CPE). First, the antiviral effect of the aqueous extracts was investigated by infecting the cell after the virus reacted with the aqueous extracts and by simultaneously adding the virus and the aqueous extracts to the cells. Then, the in vivo experiment was conducted by measuring the anti-PRRSV effect of sera collected from the mice which were previously administered with the aqueous extracts through intravenous (IV) tail vein injection. The results showed that the aqueous extracts of teas had the killing and inhibiting effect on PRRSV. The minimum inhibitory concentration of Biluochun tea (non-fermented), Pu’er raw tea (non-fermented), Tieguanyin tea (half-fermented) and Pu’er ripe tea (post-fermented) were 31.3, 31.3, 31.3, 125 µg/mL, respectively; and the corresponding minimum killing concentrations were 7.8, 7.8, 15.6, 125 µg/mL. The aqueous extracts of non-fermented tea had more obvious killing and inhibition effect on PRRSV compared to the aqueous extracts of fermented tea. Tail vein injection of tea aqueous extract does not affect the normal growth of mice, and in a short period of time, the sera from the mice injected with tea aqueous extract showed killing effect on PRRS.