Objective To investigate the expression of procalcitonin（PCT）

D-dimer（DD） and interleukin-17（IL-17） in peripheral blood of children with refractory mycoplasma pneumoniae pneumonia（RMPP） and their correlation with prognosis. Methods A total of 96 children with RMPP admitted to a hospital in Nanyang from January 2018 to January 2021 were selected as the subjects and assigned to the progression group（n=28） and the control group（n=68） following their different clinical outcomes. The peripheral blood PCT

DD and IL-17 levels were measured on the second day after admission in all children. The expression levels of peripheral blood PCT

DD

and IL-17 of the two groups were compared. Spearman correlation was used to analyze their correlation with the prognoses of the children

and receiver operating characteristic（ROC） curves were plotted to assess their predictive efficacy for RMPP disease progression. Results The levels of peripheral blood PCT

DD and IL-17 in the progression group were higher than those of the control group

and the differences were statistically significant（P<0.05）. There were significant positive correlations between peripheral blood PCT

DD and IL-17 levels and the prognosis of children with RMPP（P<0.05）. The Area Under the Curve（AUC） of peripheral blood PCT

DD

and IL-17 levels in predicting RMPP disease progression was divided into 0.657

0.678

and 0.712

with cutoff values of 0.89 ng/L

6.72 mg/L

and 2.59 ng/L

respectively

and the AUC of the combination of the three was 0.791.Conclusion The peripheral blood PCT

DD and IL-17 levels are closely related to the prognosis of children with RMPP

which have a good predictive value for evaluating the severity of the disease.