Abstract: The Thr-Gly regions of the period gene were sequenced in the five sibling species of the Drosophila auraria species complex and D.rufa.Base composition of the species complex is coherent to that of the other gene in Drosophila.The transversions are more than the transitions;the total rate of transversion to transition is 2 to 5 between pairwise species,and the rate of transversion to transition in the third codon is 2.5 to 5.The rate of synonymous (Ks) to non-synonymous (Ka) is far higher than 10.The insynonymous mutation does not exist between some species,the low Ka value indicats that the The-Gly regions in the period gene of Drosophila auraria species complex have undergone selection pressure in their evolution.The phylogenetic tree from DNA sequences of Thr-Gly regions is important to clarify the phylogenetic relationships of the species complex.