In order to breed an eugenic thin-thallus strain of Porphyra haitanensis, economic traits of hybrid and selective bred stains（Z-26, Z-61 and Z-81）were studied. It was found that: (1) The blade of Z-61 was thin and the thickness was 26-32μm. After twice cut harvest, the blade thickness (BT) showed no obvious increase and the mean thickness increase rate (TIR) was 0.32-0.35μm/d. BT of Z-81 was 36-40μm, which was 38%~50% thicker than Z-61. BT of Z-81 increased to 52μm after twice cut harvest and TIR was 0.6-0.7μm/d. BT of Z-26 was 30~42μm and TIR was 037~055μm after cut harvest. (2) After being cultured for 8 days in a medium of low N and P concentrations, the blades F-3 gametophyte of Z-61 turned yellow but were not dead; then after being cultured for 2 or 3 days in the regular medium, the color turned normal and growth recovered. F-3 gametophyte thallus of both Z-81 and Z-26 grew slower than Z-61 in a medium of low N and P concentrations, and after that spent 3 to 5 days to recover. (3) After one harvest, content of phycobiliprotein in Z-61 F-2 gametophyte was 30.21~34.40% higher than Z-26 or Z-81, and its chlorophyll-a content was 13.8~44.7% higher than Z-81. These findings provided a basis for selective breeding of a thin-thallus strain P. haitanensis, and for improving its quality and economic benefits.