Compared with Pyropia haitanensis cultivated in southern China， Pyropia suborbiculata has stronger high-temperature resistance， but its round algae are not suitable for production. Therefore， several long-type mutants were isolated from the wild-type strain of P. suborbiculata by artificial mutagenesis. In this study， the blades of the long-type mutant （CCT-2） of P. suborbiculata were induced by ⁶⁰Co-γ ray， and a new strain （PS-M1） with fast growth was screened from its progeny with growth rate as the main breeding index. The PS-M1 blades cultured at 23 ℃ for 60 days had a mean length of 68.1 cm and a length-width ratio of 26.3， which were 2.7 and 2.4 times of CCT-2， respectively. The blades of PS-M1 and CCT-2 cultured at 23 ℃ for 30 days and then cultured at 30 ℃ for another 30 days， their mean length had increased by 6.4 and 3.0 times， respectively. The survival rates of conchospores of PS-M1 and CCT-2 were 47.4 and 42.2%， respectively， after 14 days of culture at 30 ℃， with no significant difference between them. The blades cultured at 23 ℃ for 45 days had a mean chlorophyll a content of 6.5 mg/g and phycobiliprotein content of 64.9 mg/g in PS-M1， which were 20.4% and 22.9% higher than those of CCT-2， respectively. The thickness of PS-M1 was 33.6 μm， which was 15.8% thinner than that of CCT-2. The total numbers of conchospores released by PS-M1 was up to 2.223 million per shell for 10 consecutive days， which was 4.8 times that of CCT-2. In conclusion， compared with long-type mutant （CCT-2）， the new strain （PS-M1） of P. suborbiculata has a higher growth rate， better resistance to high-temperature and also shows obvious advantages in main pigments protein contents， and number of conchospores releasing， which has potential to be applied in commercial cultivation.