Abstract: Objective To investigate the distribution of pathogenic bacteria in postpartum puerperal infections and the serum C-reactive protein (CRP), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-10 (IL-10) and procalcitonin (PCT) levels. Methods Total 6 632 cases of mothers of natural delivery were selected in hospitals from January, 2017 to December, 2017. Etiological culture and drug susceptibility tests were performed on specimens of puerperal fluid, perineal incision secretions, cervical secretions, etc. of suspected maternity-infected mothers. The level of serum CRP was measured by immunoturbidimetry. The serum TNF-α, IL-6 and IL-10 levels were determined by enzyme-linked immunosorbent assay (ELISA). Results There were 246 cases of maternal puerperal infection in 6 632 cases, the infection rate was 3.71%. Postpartum puerperal infection sites were perineal wound infections, respiratory infections, and breast infections. The constituent ratios were 73.98%, 17.07% and 8.94%, respectively. Among 246 cases of puerperal infection, 297 strains of pathogenic bacteria were cultivated. The main pathogens were Escherichia coli, Streptococcus agalactiae, and Enterococcus faecalis, accounting for 45.12%, 23.91% and 15.82%, respectively. The resistance rates of Escherichia coli to penicillin, lincomycin, azithromycin, cefazolin, and compound sulfamethoxazole were relatively high, and the drug resistance rates were 100.00%, 95.52%, 85.07%, 83.58% and 80.60%, respectively. The resistance rates of Streptococcus agalactiae to penicillin, piperacillin, ciprofloxacin and lincomycin were relatively high, and the drug resistance rates were 100.00%, 100.00%, 98.59% and 97.18%, respectively. Enterococcus faecalis had high resistance rates to penicillin and lincomycin, and the resistant rates were 100.00% and 89.36%, respectively. The serum levels of CRP, TNF-α, IL-6 and IL-10 in the puerperal infection group were higher than those in the puerperal uninfected group (P<0.05). Conclusion The most common pathogens for postpartum puerperal infections of natural labor are Escherichia coli, Streptococcus agalactiae, and Enterococcus faecalis. The main pathogens are highly resistant, and maternal serum levels of TNF-α, IL-6 and IL-10 are increased.