Abstract: 【Objective】The strictosidine synthase gene of Gelsemium elegans Benth（GeSTR）was cloned and its expression pattern was analyzed to provide theoretical reference for the investigation of the regulation mechanism of this gene in the biosynthesis of gelsenicine.【Method】The relative contents of gelsenicine between the different tissues of Gelsemium elegans Benth were obtained by liquid chromatography-mass spectrometry（LC-MS），and GeSTR，a related enzyme gene for the synthesis of gelsenicine，was filtered by the co-expression correlation analysis method of“genome+expression profile+metabolome”，and coding region sequence（CDS）of the GeSTR gene was cloned by PCR，and sequence analysis in combination with bioinformatics software was conduct. The expression pattern of GeSTR gene among different tissues was obtained by real-time fluorescence quantitative PCR.【Result】The relative content ranking of gelsenicine content in different tissues was as follows：root>flower>stem>leaf，the strongest gene correlated with gelsenicine， GeSTR，was screened by combining the information of the expression profiles of the 14 candidate STR genes. The open reading frame（ORF）of GeSTR gene was 1026 bp in size，encoding a total of 341 amino acids residues，with a theoretical molecular weight of 38.31269 kD，a theoretical isoelectric point（pI）of 5.69. Aliphatic index and instability index II were 85.95 and 30.19 respectively，and the grand average of hydropathicity（GRAVY）was -0.158，which speculated that GeSTR protein was a stable hydrophilic protein. GeSTR protein was mainly located in the 2 subcellular structures，the extracellular matrix and chloroplasts. It contained signal peptide and transmembrane region at N terminal，and might be a secretory protein. The protein also had 32 potential phosphorylation sites and 1 N-glycosylation site. Its secondary structure consisted of random coil（41.64%），extended strand（32.85%），α-helix（15.54%）and β-fold（9.97%）. The GeSTR protein not only contained the typical structural domains of STR，but also the YvrE structural domains，which shared similarities with those of STR amino acid sequences of other 11 plants，with the highest similarity（up to 93.84%）and nearest relationship to the STR protein of Gelsemium sempervirens. The results of real-time fluorescence quantitative PCR showed that GeSTR gene was only expressed in roots and flowers of Gelsemium elegans Benth，and its relative expression level in flowers was significantly higher than that in roots（P<0.01），with as 4.25 times as that in roots，indicating that the expression of GeSTR in Gelsemium elegans Benth was tissue-specific.【Conclusion】The relative content of gelsenicine in roots and flowers of Gelsemium elegans Benth is higher than that in stems and leaves，and the GeSTR gene is only expressed in roots and flowers. Therefore，it is hypothesized that GeSTR gene positively regulates the synthesis of gelsenicine and has the role of catalyzing the coupling reaction to produce strictosidine as well as a variety of other potential functions，which will provide clues for the subsequent studies on the pathways and mechanisms for the synthesis of gelsenicine and other MIAs.