In this study, a CsBAP1 gene was cloned from the cDNA of ‘Longjing 43’ based on the transcriptome data of tea plant. We analyzed its protein sequence characteristics and gene expression patterns. In addition, the expression profiles of the CsBAP1 gene in different tissues and under extreme temperatures and hormone treatments in tea plant was analyzed by quantitative real time PCR. (1) Sequence analysis showed that the length of the CsBAP1 open reading frame (ORF) is 543 bp, encoding 180 amino acids and contains a highly conserved region called C2 domain. Protein analysis suggested that the CsBAP1 is a hydrophilic protein with the theoretical relative molecular weight 19 398 Da and the theoretical isoelectric point 9.30. Secondary structure prediction showed that the CsBAP1 protein consists of 8.89% αhelix, 7.78% βturn, 35.56% extended strand and 47.78% random coil. The threedimensional structures indicated that CsBAP1 protein contains αhelix and βstrands. (2) The expression profiles of the CsBAP1 was detected in flower, floral buds, young leaves, mature leaves and senescent leaves by the RTqPCR. And the highest expression level was detected in the senescent leaves. The expression level of CsBAP1 was downregulated by ABA, IAA, MeJA, GA₃, and SA treatments, respectively. The expression level of CsBAP1 was upregulated under high temperature (38 ℃), low temperature (4 ℃), drought (200 g·L^-1 PEG), and highsalinity (200 mmol·L^-1 NaCl) treatments, respectively. These results provide a foundation for the function study of CsBAP1 gene in tea plants.