Objective:To explore the characteristics of type 3 secretion system and biofilm of Pseudomonas aeruginosa in diabetic foot wound, and to analyze the relationship between these factors, as well as to the antibiotic sensitivity.Methods:Thirty-three strains of Pseudomonas aeruginosa were collected from the foot wounds of diabetic foot inpatients in Tianjin Medical University Chu Hsien-I Memorial Hospital from February 1, 2018 to December 31, 2018. Thirteen strains of Pseudomonas aeruginosa were collected from non-diabetic wounds. All strains were tested for antibiotic sensitivity. The virulence genes exoS or exoU of Pseudomonas aeruginosa and the ability of biofilm formation were tested. The characteristics of exoS or exoU and biofilm of Pseudomonas aeruginosa were analyzed. Patients′ clinical outcomes were also analyzed.Results:Pseudomonas aeruginosa with exoS gene was the major pathogen, 90.9% found in diabetic foot group and 84.6% in control group, with no significant difference( χ2=0.54, P=0.46). The drug-resistant strains of Pseudomonas aeruginosa with exoS accounted for 16.7% in diabetic foot group and 18.2% in control group, also with no significant difference( χ2=0.18, P=0.83). There were 5 strains of Pseudomonas aeruginosa carrying exoU, 3 strains in diabetic foot group, of which 1 was resistant, 2 in control group, no resistant strain. Pseudomonas aeruginosa increased the ability of biofilm formation in diabetic foot group, accounting for 57.6%, and for resistant strains, 83.3% of them increased the biofilm formation ability. Two kinds of Pseudomonas aeruginosa produced different biofilms, but they were effectiveless for carbapenem antibiotics. The times of debridement ( P<0.01), time of antibiotic use ( P<0.01) were more in biofilm wound, but the healing rate reached 75%-90%. Conclusion:Pseudomonas aeruginosa secreting ExoS is the main one in the diabetic foot wound. The ability of Pseudomonas aeruginosa to produce biofilm in DF wound is increased. Biofilm is one reason for its antibiotic resistance. Multiple debridement combined with sensitive antibiotics is an effective method to remove biofilm.