The bacterial wilt(Pseudomonas solanacearum)of eucalyptus(Eucalyptus tereticornis)and equisetum(Casuarina equisetifolia)are important diseases in South China. This paper reports the bactericidal effect of antibacterial peptide from the Chinese oak silkworm(Antheraea pernyi)on the pathogens of bacterial wilt of eucalyptus and equisetum. Antibacterial peptide was induced in Chinese oak silkworm pupae by injecting Escherichia coli K12D31.Antibacterial peptide was purified from the haemo-lymph with CM-Sepharose CL-B6 and phenyl sepharose 4B. The purified antibacterial peptide had a molecular mass of a substanee of 4000 u and was labelled with fluo-rescent yellow. The pathogens wers treated with 10 mg/L of antibacterial peptide and observed under the scanning electron microscopy and laser scanning confocal imaging system to study how the antibacterial peptide inhibited and killed the bacteria.The result showed that the primary taget was the cell membrane. the fluorescent substances aggregated surrounded and embraced the surface of the bacterial membrane.then permeated into the cell and distroyed the membrane. Some small channels were found on the surface of the cell, the intracellular substances were forced out of the cell and finally the cell became empty and died.