Objective To analyze the value of serum ferritin(SF)in the early diagnosis of Mycoplasma pneumoniae pneumonia(MPP)based on decision curve analysis(DCA)and dose-response relationship.Meth-ods A total of 104 MPP patients in Taizhou People's Hospital from October 2016 to October 2021 were se-lected as the MPP group,and 90 healthy adults who underwent physical examination in Taizhou People's Hos-pital during the same period were selected as the healthy group.The clinical data of the two groups were com-pared.The influencing factors of MPP in patients were screened.The diagnostic value of SF for MPP was analyzed,the best cut-off value was sought,and the clinical predictive value of SF for MPP was evaluated.Results White blood cell count,C-reactive protein,tumor necrosis factor-α,lactate dehydrogenase,SF were independent risk factors for MPP,and 25-hydroxyvitamin D was its protective factor(P＜0.05).The dose-response relationship analysis showed that there was a nonlinear dose-response relationship between the continuous change of SF and MPP(P＜0.05).When SF＞127.68 ng/mL,the risk of MPP increased with the increase of SF level.DCA analysis showed that SF had important clinical value in the early prediction of MPP.Conclusion SF has a high value in the early diagnosis of MPP,and there is a nonlinear dose-response relationship between SF and MPP.When SF＞127.68 ng/mL,the risk of MPP increases with the increase of SF level.