Abstract: A DNA polymerase, having an amino acid sequence represented by SEQ ID No. 2, or a derivative of the amino acid sequence by substitution, deletion, or addition of at least one amino acid residue. The DNA polymerase is a hybrid DNA polymerase prepared by inserting a thioredoxin binding domain (TBD) of bacteriophage T7 DNA polymerase into a DNA polymerase I (Sau) of Staphylococcus aureus. A method for preparing the DNA polymerase includes: 1) determining a corresponding position and a target substitution sequence in Sau protein for the TBD of the bacteriophage T7 DNA polymerase; 2) devising and synthesizing a primer according to a gene sequence of Sau and a sequence TBD published by GenBank; 3) cloning the Sau-TBD segment acquired in (2) to an expression vector pTrc99A to construct a recombinant vector pTrc99A-Sau-TBD; and 4) transforming Escherichia coli by the recombinant vector pTrc99A-Sau-TBD and inducing protein expression.