Abstract: The full-length cDNA of chs gene of Osmanthus fragrans was cloned which was related to color formation, the characteristics of the gene sequence and evolution relationships were analyzed to provide a theoretical basis for exploring gene function in the form of color. In this study, a full-length cDNA sequence of chs gene was obtained from Osmanthus fragrans by using RT-PCR and RACE. The gene nucleotide and amino acid sequences were analyzed by using NCBI and DNAMAN and a phylogenetic tree was constructed by using DNAMAN software directly, which would help analyze the gene evolutionary relationships among different species. Result showed that: the full-length gene was cloned from Osmanthus fragrans successfully, which was displayed as Osmanthus fragrans chs gene, which was 1383 bp in full length and included 5′URT of 48 bp and 3′ URT of 162 bp, had an open reading frame of 1173 bp encoding a deduced polypeptide of 390 amino acids. Sequence analysis revealed that this gene had 3 active sites: Cysl64, His303 and Asn336, and 2 decisions substrate specificity of phenylalanine residues: Phe215 and Phe265. Ofchs had 2 characteristics of polypeptide sequence of chs synthase superfamily: RFMMYQQGCFAGGTVLR and GVLFGFGPGL. Blast sequence showed that similarity between Osmanthus fragrans and Olea europaea was up to 95% and was at around 72%-76% with the other dicots. Ofchs gene belonged to chs family, phylogenetic analysis showed that the gene cluster had the distinct species characteristics, Osmanthus fragrans had a near relationship to Labiatae, which was up to 76%, and it was in line with plant taxonomy, and laid the foundation to explore the mechanism of Ofchs in the formation of the color line for the future.