The acute toxicity of three kinds of typical Pu’er tea and one kind of baked green tea from Yunnan province were evaluated in this investigation. The tested mice were feed with tea infusion. The LD₅₀ of the three kinds of Pu’er Tea was 9.7βg/kg, 11.2 βg/kg and 12.2 βg/kg respectively, while that of the baked green tea was 7.5βg/kg. None of tested mice died 14 days later, when single feeding dose of four kinds of tea was less than 5βg/kg. Most tested mice showed excitement when the feeding dose less than 1/2 of LD₅₀. The tested mice revealed symptoms of restrained nervous 10 minutes late with the feed dose increased. There was only one peak of the acute lethal time in the case of Pu'er tea, and two peaks appeared in the case of baked green tea. The authors regarded that the death of tested mice was attributed to the high concentration of caffeine and polyphenols. It is concluded that all four kinds of tea are highly safe for drinking according to LD₅₀. However , scientific drinking methods should be mentioned first.