Abstract: To understand the natural distribution and genetic relationship of Porphyra species in coastal areas of Guangdong Province, we collected samples from Pingyu Island, Wailingding Island and Xiachuan Island of Guangdong Province in December, 2012 for DNA sequence analysis of the large subunit of ribulose-1-5-bisphoshoate carboxylase/oxygenase enzyme (rbcL) and nuclear SSU ribosomal RNA (nrSSU) gene as well as cytological observations. The results show that P.haitanensis, P.dentata and P.crispata were the dominate species from Pingyu Island, while P.crispata and P.ramosissima were the dominate species from Wailingding and Xiachuan Islands. All the four species, which were all warm-temperature species and belonged to Porphyra, had five chromosomes (n=5) with undulated margin. The chromosome of P.ramosissima was firstly reported within Porphyra spp. Based on the analysis of DNA sequences of rbcL and nrSSU, P.crispata from Wailingding and Xiachuan Islands had much closer relationship with P.crispata from Pingyu Island, while P.crispata from Pingyu Island had the closest genetic relationship with P.haitanensis and the farthest relationship with P.ramosissima. The rbcL and nrSSU genes of P.ramosissima and the nrSSU genes of P.crispata had been firstly amplified in this study, which provides basic data for the systematics of Porphyra.