Porphyra haitanensis is an economically important marine crop in southern China. Due to global warming, farming of P. haitanensis was seriously affected by the increasing water temperature. In this study, the gametophytic blades of an F4 high temperature tolerance line (Z-61) and wild-type line (WT) were grown at normal temperature (21℃) and high temperature (30℃) under non-aerated condition for 0, 2, 4, 6, 8 and 10 days. Changes in four quality indices were measured, including contents of pigment, crude protein, total amino acids and free amino acids. The results showed that the quality of Z-61 was not significantly affected by the normal temperature and non-aeration. The quality of wild-type strain was even improved after a short-term cultivation under normal temperature and non-aeration, but the quality of Z-61 and wild-type strains were seriously affected by the high temperature and non-aeration stress. Furthermore, the results also indicated that the Z-61 could enhance its ability of high temperature tolerance by increasing the content of allophycocyanin (APC) and free amino acids. Our results would be helpful for understanding the mechanism of high temperature tolerance of P.haitanensis.