At normal situation, algae maintain a balance between reactive oxygen species (ROS) production and scavenging states, and a little amount of ROS molecules can be used as intracellular signal transduction molecules involved in biochemical metabolic processes. But under abiotic stress conditions, excessive accumulation of ROS will cause oxidative damage to cell membrane, then resulting in irreparable loss of metabolic function and eventually leading to cell death. Algae evolved a complex antioxidant defense mechanism (including non-enzymatic system of antioxidant enzymes and antioxidant enzymatic systems) to resist the damages of ROS. Glutathione peroxidase (GPX) is an important member of the ROS scavenging enzymatic system, which can clean the lipid peroxide and H2O2, its mechanism is to reduce ROS through catalytic the reactions between glutathione (GSH) and lipid peroxides (ROOH) or free H2O2, thereby blocking the production of free radicals, inhibiting the peroxidation processes of cells and protecting the enzyme activity of some sulfhydryl. Previous studies have concluded that the level of GPX activity has a positive correlation with the ability of plants to adapt to adversity. So GPX synthesis-related gene has been considered as an important stress resistance-related gene. Pyropia haitanensis, naturally growth in coastal intertidal zone, is an important economic macroalgae in Fujian, Zhejiang, Guangdong provinces. With tidal changes, the thallus required to undergo periodic dehydration and rehydration process, therefore it should has a very strong adaptability to adversity. Simultaneously, with global warming, the temperature of sea water increases, which causes damages to seedling of P. haitanensis and lead to big economic loss for aquaculture industry. As for the physiological and molecular response of P. haitanensis to high temperature and dehydration stress conditions, our previous studies found GPX plays an important role in stress resistance. In this study, the full-length of GPX gene from Pyropia haitanensis was cloned by using rapid amplification of cDNA ends (RACE) technology, which named PhGPX (GenBank accession: JX673908). The nucleotide sequence of PhGPX consists of 1027 bp, including an open reading frame (ORF) of 555 bp, which can be translate into a 184-amino-acid putative peptides with a molecular mass of 19.91 kD and a theoretical PI of 8.76. Multiple sequence alignment and Phylogenetic analysis indicated that the protein belong to the plant GPX enzyme family. Expression patterns analyzed by qPCR revealed that the expression of PhGPX gene between the thallus phage and conchocelis phage was not significantly different; during high-temperature stress, the expression levels of PhGPX significantly upregulated firstly and then decreased; However, during desiccation, the expression levels of PhGPX had no significantly change when the water loss was ≤40%, but as the desiccation continue, the expression levels of PhGPX were significantly downregulated. These results suggested that the expression of PhGPX was induced by different stress at different levels.