Porifera (sponge) has been considered the earliest branching group of the metazoan crown, it plays an important role of evolution from protist to multicellular organisms. The sponges do not have tissues and organs. There are 15,000 species of sponges in the world. They contain a rich variety of secondary metabolites which may have the potential of becoming anticancer or antivirus drugs. The morphological characteristics of sponges may be affected by the environmental conditions and cause ambiguity and confusion in sponge identification. The complete mitochondrial DNAs of four Demospongiae sponges, Terpios hoshinota, Xestospongia testudinaria, Petrosia corticata, and Suberea clavata in Green Island were determined by PCR and primer walking. The sequences can be used for evolution and phylogenetic analyses. The complete mitochondrial genomes of the four sponges contain 20498 bp, 18988 bp, 18562 bp and 19559 bp, respectively. The genomes encode 2 rRNA genes (rns, rnl), 14 protein-coding genes (atp6, atp8-9, cox1-3, cob, nad1-6, and nad4L) and 25 tRNAs. All the genes of T. hoshinota, X. testudinaria, P. corticata are transcribed on the same strand. Whereas, some of the genes (nad 4L ~ tRNA-SerUGA) of S. clavata are encoded on the complementary strand. The results showed the differences between the mitochondrial DNA sequences of X. testudinaria and the Atlantic sponge, X. muta, are very limited, therefore, they may be reclassified as the same species. Meanwhile, S. clavata and Aplysina fulva are close phylogenetically. The conflict between molecular and morphology taxonomy should be re-examined.