To investigate the infection situation of Klebsiella pneumoniae of pregnant women with polycystic ovary syndrome (PCOS), and to study its influence on the pregnancy outcomes of these women. Methods: From May 2020 to July 2021, 113 pregnant women with PCOS were included and were divided into group A (43 women with Klebsiella pneumoniae infection) and group B (40 women without Klebsiella pneumoniae infection), and other 30 healthy pregnant women were included in group C. The distribution of pathogens was analyzed. The situation and clinical characteristics of the women with Klebsiella pneumoniae infection were analyzed. The adverse pregnancy outcomes of the women with Klebsiella pneumoniae infection and its influence factors were also analyzed. Results: There was significant difference in the rate of Klebsiella pneumoniae infection among the women with <25 years old (13.0%), the women with 25-29 years old (8.3%), the women with 30-34 years old (18.2%), the women with 35-39 years old (4.2%), and the women with ≥40 years old (5.0%) (P＜0.05). Gram-negative bacteria infection was the main pathogens of the women in group A, the rate of which was 70.9%. The total incidence of ectopic pregnancy, chromosomal abnormality, early abortion, induced labor, and polyhydramnios (46.5%) of the women in group A was significantly higher than that (22.5%) of the women in group B and that (26.7%) of the women in group C. The total incidences of miscarriage, preterm birth, FGR, macrosomia, and stillbirth (79.1%) of the women in group A was significantly higher than that (36.7%) of the women in group C. The total incidence of gestational diabetes mellitus, premature rupture of membranes, mycotic vaginitis, polyhydramnios, and late-pregnancy hypertension (65.1%) of the women in group A was significantly higher than that (23.3%) of the women in group B and that (40.0%) of the women in group C (all P＜0.05). The antibiotics used ≥2 kinds, mechanical ventilation duration ≥7 days, and renal insufficiency of the women with PCOS were the influencing factors of their multidrug-resistant Klebsiella pneumoniae infection. Conclusion: Klebsiella pneumoniae infection of the pregnant women with PCOS is mainly infected by gram-negative bacteria, and which is closely related to the pregnancy outcomes of these women. Different treatment methods of Klebsiella pneumoniae infection are the influencing factors of the pregnancy outcomes of these women.