Anti-microbial photodynamic technology(APDT) on L.monocytogenes was conducted using photo sensitizer hematoporyrin monomethyl ether(HMME) followed by tungsten-halogen lamp(power density 200 mW/cm2).The bactericidal effects were measured by counting the reduction of colony forming unit(CFU) after APDT-HMME treatment.The degradation of protein was observed under sodium dodecyl sulphate polyacrylamide gel electrophoresis(SDS-PAGE),and the damage of DNA was investigated by polymerase chain reaction(PCR).Approximately 99.9999% of L.monocytogenes were photo inactivated by illumination with 30 min visible light in the presence of 25 μg/mL HMME.The cell killing effect to L.monocytogenes with illumination was much greater than in the dark at the same concentration of HMME.The protein of L.monocytogeneirradiated with HMME and visible light for 30 min was degraded obviously shown by SDS-PAGE graph and the DNA damage shown by PCR graph was greater in APDT-treated groups compared with the control groups.The significant cell killing effect of APDT-HMME on L.monocytogenes may be explained by the bactericidal mechanism through the degradation of the protein and the damage of DNA.