Bst II DNA Polymerase Large Fragment is obtained from the large fragment of Bacillus stearothermophilus DNA Polymerase by directed genetic engineering. It contains the 5´→ 3´ polymerase activity and strong strand displacement activity, but lacks 5´→3´ exonuclease activity. It is applicable for isothermal amplifications such as LAMP (Loop-Mediated Isothermal Amplification), HDA (Helicase-Dependent Amplification) and RCA (Rolling Circle Amplification). Compared with the previous generation, Bst II DNA Polymerase Large Fragment has superior amplification speed, dUTP tolerance, salt tolerance and thermal stability.