Objective To investigate the relative factors of serum pertussis toxin antibodies (PT-IgG) in children with pertussis.Methods Clinical data of children hospitalized with pertussis from April 1, 2018 to July 31, 2019 were retrospectively analyzed. To analyze the influence of different course of disease, pertussis vaccine dose, onset age and disease severity on PT-IgG level in children with pertussis. Result A total of 638 children were included. In the unvaccinated group, 313 patients (177 boys and 136 girls) had a median age of 78.0 (52.0-125.0) days. In the vaccination group, there were 325 patients (163 boys and 162 girls) with a median age of 232.0 (144.0-483.0) days. There were statistically significant differences in the distribution of PT-IgG levels among different disease course groups at sampling (≤14d, 15-21d, >21d) in the unvaccinated group (P<0.01). The proportion of PT-IgG≥80 IU/mL was higher in patients with disease course >21 days. There was significant difference in PT IgG level between different vaccine groups (P<0.01). The proportion of PT-IgG≥80 IU/mL was higher in patients with disease course of 15~21 days and >21 days. There were statistically significant differences in PT-IgG levels between groups receiving different doses of vaccine (P<0.01). The levels of PT-IgG gradually increased with the increase of vaccine doses. In the unvaccinated group, no matter in the severe group or the normal group, the difference of PT-IgG level among different disease course groups at sampling was statistically significant (P<0.05). In the inoculation group, the difference of PT-IgG levels among different disease course groups at sampling in the normal group was statistically significant (P<0.05).Conclusions The level of PT-IgG in children with acute infection of Bordetella pertussis in China was not high, and 59.9% of them had a PT-IgG level lower than 20IU/mL. PT-IgG levels were affected by the dose of vaccine and the course of disease at the time of sampling.