Abstract: The γ-aminobutyric acid ( GABA) , L-theanine and L-glutamic acid contents in different black tea were determined by high-performance liquid chromatography ( HPLC) , and the effects of black tea water extract at different main amino acids contents on the locomotor activity of mice were monitored using a mouse activity monitor system. The results showed that the contents of GABA, L-theanine and L-glutamic acid were different in the different black tea samples, and the content of L-theanine was higher than that of GABA and L-glutamic acid. Among them, the GABA content in Gaoligongshan was the highest, followed by Haishuiyun black tea, and Zijuanhong was the lowest; the L-theanine and L-glutamic acid contents in Baxian black tea were the highest, followed by Haishuiyun black tea, and India Darjeeling black tea were the lowest.Additionally, the result of animal experiment showed that the locomotor activity level in the black tea with higher main amino acids content group was significantly decreased compared with that in the black tea with lower main amino acids content group ( p < 0.05) .The above results suggested that black tea with a high content of main amino acids had a significant sedative effect on mice.