Abstract: The characteristics of the improved strain SF-2 were evaluated and compared with the improved variety SF-1 and the wild type of Porphyra haitanensis according to the results of the laboratory studies and pilot scale tests in mariculture farm.There were significant differences between SF-2 and WT in growth rates,contents of phycobiliprotein,thicknesses of the blades and yields of pilot cultivation.The absolute growth rates of SF-2 blades were significantly higher than those of WT.The length of 90-day-old SF-2 blades was(391.6?47.37) cm which was about 10 times longer than WT.There were five peaks in the in vivo absorption spectra of SF-1,SF-2 and WT blades between wavelengths of 350-750 nm,and the peak values of SF-1 and SF-2 were almost the same,but both higher than those of WT.The phycobiliprotein content of SF-2 blades was (90.81?3.98) mg/g which was slightly higher than SF-1 and was 1.95 times higher than that of WT.The mean thickness of SF-2 blades was(31.95?4.16) μm,which was 14.0% and 38.7% thinner than that of SF-1 and WT,respectively.The number of the released conchospores per shell of SF-2 conchocelis in mariculture farm was 286 000,which was 43.0% more than that of that of SF-1 and was sufficient in cultivation.The fresh yield of SF-2 of the first four harvests was 240 000 kg,which increased by 30.1% compared with WT and by 6.7% compared with SF-1,resepectively.It came to a conclusion that the superiority of the improved strain SF-2 possesses the value to be applied and disseminated.