Abstract:Porphyra haitanensis has degenerated in breed and has a reduced outcome and descent quality recent ten years. The blades were guided to variation in order to select and cultivate new strains of Porphyra haitanensis that were high quality and high yield. 60Co-γray was a useful mutagen in induced mutation breeding .After treated with 60Co-γray ,free-living conchocelis of wild Porphyra haitanensis were induced and represented in offsprings. Purple mutant and excellent practical characters strains were selected from a lot of gametophytic blades. Single cell clone and enzymolysis were used to propagate fast in pure strains of induced mutations. Moreover, the central practical characters of mutant strains were studied: ①The first one was 7-I , which were wide blades (2.99±0.61)cm, grew faster (the length mean daily increase was 6.51 cm and it was 55.3% faster than control group when the length of the blades beyond 30 cm), was a high temperature resistant strain (it was grew normally at 29 ℃ and the resistant temperature was 2℃ more than control group ) and total phycobiliprotein content was high (104.858 mg·g-1 of dry sample, improved by 39.0%). ② The second one was 7-Ⅱ, which were narrow blades, had quick growth (the length mean daily increase was 4.26 cm and it was 58.7% faster than control group when the length of the blades beyond 30 cm), was a thin-blade strain (it was 22.5-27.5 μm in the middle part of the blade and was 29.6% thinner than control group) and total phycobiliprotein content was high (104.239 mg·g-1 of dry sample, improved by 39.4%) ③The third one was pigementation mutant, 3-I, which possessed of purple and thin blade(25.0-32.5 μm).④The yield of 7-I and 7-Ⅱ was 291.5-309.6 kg·666.6 m-2,which was 29%-37% higher than control group. The results laid a solid foundation for germplasm improvement and exploitation of fine variety of Porphyra haitanensis.