Abstract: The potato steroidal glycoalkaloids (SGAs) is an important secondary metabolites in solanaceae and liliaceae. It is closely related to the antireversion force of plan itselfe and product quality, simultaneously, it has a wide pharmacological activity in pharmacology. Solanidine: UDP-glucosyltransferase(SGT) was the key enzyme of the terminal of SGAs anabolic pathway in Solanum tuberosum.Studying the gene structure and its encoding enzyme protein characteristic plays an important role in the process of the regulation of SGAs synthesis and production of SGTs by microbial fermentation in plant. Analyzing the structure and properties of three enzyme protein encoded by glycosyltransferase cDNA structure and properties by bioinformatics method. Total RNA was extracted from stem of S. tuberosum and three glycoalkaloid synthase gene (SGT1, SGT2 and SGT3) fragment was obtained by reverse transcription polymerase chin reaction (RT-PCR). It was cloned into pMD^R19-T vector and the positive clones identified by PCR were sequenced. Three SGT enzyme gene fragments were gained from stem of S. tuberosum, each of which contains 1 467-1 518 bp and encodes a peptide of 488-505 amino acids. Similarity comparisons show that they share over 99.12% similarity in nucleotide sequence and over 99% similarity in amino acid sequence with those of other plant SGTase gene (U82367.2, DQ 218276.1 and DQ 266437) in GenBank, UDPG glycosyltransferase conserved domain and many important functional sites. the PI=5.52-5.62. The 3D structure of protein was predicted by homology comparative modeling in Swiss-Model, the results showed that the 3D structure of SGT was highly similar to that of the glycosyltransferase, so it was inferred that SGT3 should be a member of glycosyltransferase superfamily that has function of steroidal glycoalkaloid. sgt1, sgt2 and sgt3 similar gene obtained here was rhamnosyl transferase gene, and its sequence was submitted with GenBank: sgt1, No: JN695005; sgt2, No: JN695006; sgt3, No: HM188447.