Abstract: To understand the codon bias of auxin receptor gene TIR1，one TIR1 gene of Dimocarpus longan was analyzed by CodonW，SPSS and EMBOSS online program，and then compared with another longan genes，TIR1 genes from 29 plant species and genomes of model organisms. The results showed that the codon bias levels of TIR1 and genome of Dimocarpus longan were low，and they were bias toward the synonymous codons with A and T at third codon position. The cluster tree of TIR1 based on CDS could reveal the evolutionary relationship much better among different species than the result analyzed by RSCU（Relative Synonymous Codon Usage）. According to codon usage frequency，the yeast expression system was more suitable for heterologous expression of TIR1，and the difference of codon bias between D. longan TIR1 gene and model plant genomes were not significant，but Nicotiana sylvestris and Solanum lycopersicum may be the best receptors for transgenosis of this gene.

Key words: Dimocarpus longan, codon bias, auxin receptor, cluster analysis