The invention relates to engineered escherichia coli, and also provides a preparation method of engineered escherichia coli. The preparation method comprises the following steps: cloning cDNA (complementary Deoxyribose Nucleic Acid) of a gene of phanerochaete chrysosporium lignin peroxidase; performing double digestion on the cDNA; connecting the digestion fragments with a pCold-TF vector; authenticating whether the obtained plasmid pCold-TF-LiP is subjected to positive expression; and introducing the positive plasmid pCold-TF-LiP into escherichia coli BL21 competent cells to obtain the engineered escherichia coli for expressing lignin peroxidase. The invention also provides an application of the engineered escherichia coli, namely, inoculating the engineered escherichia coli into a liquid culture medium, adding ampicillin to the liquid culture medium, culturing until OD600 (Optical Density) reaches 0.58 to 0.62, and adding a protein inductive agent IPTG (Isopropyl Thiogalactoside) to induce the expression of recombinant protein. The engineered escherichia coli is high in expression quantity and extremely high in activity, and the enzyme activity reaches 3,528U/L.