Abstract: Two variants of EcHcL1 and 2 based on Exopalaemon carinicauda transcriptome library were obtained by using RACE technique. The total length of EcHcL1 and 2 were 2248 bp and 2121 bp, which encoded protein of 685 and 676 amino acids, respectively. EcHcL1 and 2 are relatively conservative in evolution, and has typical domains of hemocyanin, including copper ion binding region, conserved His site and Ig-like region. EcHcL1 may relate to pigment metabolism and phenoloxidase activity because of more than a tyrosinase domain. The results of tissue expression distribution showed that EcHcL1 and 2 were expressed in all the 10 tissues, and higher expressed in hepatopancreas and haemocytes. Different variants of E. carinicauda hemocyanin subunit may also have various immunological functions. The expression of the 2 variants of mRNA after pathogen stresses were investigated using the Real-time PCR strategy. The results showed that EcHcL1 had higher expression level during 12—48h after Staphylococcus aureus, Vibrio parahaemolyticus and WSSV challenges, and its among more 1.5—4 times higher than that in control group. The expression level of EcHcL2 reached the highest value among 24—48h after stress, which increased 2—9 times compared with the control group. Therefore, we speculated that the E. carinicauda hemocyanin subunit variants may related to immune defenses closely and might have antimicrobial resistance activity.