Abstract: The hyperthermo-piezophilic heterotrophic archaeon Thermococcales including Palaeococcus spp., are an important order in deep sea hydrothermal fields as the group contains versatile extracellular hydrolases for nutrient absorption.This study analyzed the thermostable activity and sequence of its amylase to understand the adaptation mechanism of Palaecoccus pacificus DY20341^T in hydrothermal fields. Enzyme activities were investigated by DNS method and Native-PAGE. The conserved sites, domains and signal peptide were further analyzed by sequence analysis. Four amylase were found in the genome of P.pacificus DY20341^T, i.e. extracellular α-amylase (PAP00275), extracellular cyclodextrin glucanotransferase (PAP01075), intracellular α-amylase (PAP09095) and intracellular 4-α-glucanotransferase (PAP09225) with their conserved domains. The crude amylase showed a good stability in temperatures of 60-110 ℃, with the highest activity at 100 ℃. It shows that as an important environmental adaptation mechanism the strain DY20341^T can increase the amylase numbers with characters of high temperature tolerance and enzyme synergy to help it adapt to high temperature and limited nutrients in deep-sea hydrothermal environments.