Relating to the technical field of molecular biology and genetic engineering, the invention aims to provide preparation and application of a Bemisia tabaci peptidoglycan recognition protein with bactericidal activity. The nucleotide sequence of a Bemisia tabaci peptidoglycan recognition protein coding gene is shown as SEQ ID NO.1. The Bemisia tabaci peptidoglycan recognition protein BtPGRP gene and the coding nucleotide sequence provided by the invention enable application in escherichia coli to express new protein and coding sequence. Bacteriostatic experiment of the purified recombinant protein with bactericidal activity shows that: recombinant Bemisia tabaci peptidoglycan recognition protein gene BtPGRP prokaryotically expressed recombinant protein has the ability of combining gram-negative bacteria and gram-positive bacteria, and can kill gram-negative bacteria and gram-positive bacteria at the same time. Further, application of the method to production through existing genetic engineering approaches has potential application value in development of broad-spectrum antibacterial drugs, novel immunopotentiators, feed additives and other aspects.