Objective:To investigate the change and clinical significance of macrophange inflammtory protein-1α (MIP-1α) and human cartilage glycoprotein 39 (YKL-40) levels in serum and cerebrospinal fluid of children with mycoplasma pneumonia complicated with encephalitis.Methods:A total of 108 children with mycoplasma pneumonia treated in Shishou People′s Hospital from July 2018 to May 2020 were retrospectively selected as the study objects, including 66 patients with encephalitis and 42 patients without encephalitis. Fifty-three healthy children who participated in physical examination during the same period were selected as the normal control group. The levels of MIP-1α and YKL-40 in serum and cerebrospinal fluid were detected by enzyme-linked immunosorbent assay (ELISA). Pearson test was used for correlation analysis. Receiver operating characteristic (ROC) curve was used to evaluate the diagnostic value of MIP-1α and YKL-40 levels in serum and cerebrospinal fluid for mycoplasma pneumonia complicated with encephalitis.Results:The serum levels of MIP-1α and YKL-40 in the encephalitis group and without encephalitis group were higher than those in the normal control group: (84.82 ± 12.85) and (63.46 ± 9.23) mg/L vs. (24.12 ± 2.45) mg/L, (53.46 ± 9.25) and (31.45 ± 7.35) ng/L vs. (23.95 ± 6.38) ng/L, and the serum levels of MIP-1α and YKL-40 in the encephalitis group were higher than those in the without encephalitis group, there were statistical differences ( P<0.05). The cerebrospinal fluid levels of MIP-1α and YKL-40 in the encephalitis group were higher than those in the without encephalitis group: (124.82 ± 20.85) mg/L vs. (113.46 ± 18.23)mg/L, (46.46 ± 10.25) ng/L vs.(22.95 ± 5.38) ng/L, there were statistical differences ( P<0.05). The results of Pearson test showed that the levels of MIP-1α and YKL-40 in serum and cerebrospinal fluid had positively correlated ( r = 0.697, 0.403, P<0.05). ROC curve analysis results showed that the area under the curve (AUC) of serum YKL-40 and MIP-1α levels in the diagnosis of children with mycoplasma pneumonia complicated with encephalitis was 0.845 and 0.885, respectively, and the AUC of combined YKL-40 and MIP-1α levels in the diagnosis of children with mycoplasma pneumonia complicated with encephalitis was 0.943, higher than the level of single index detection. Conclusions:The levels of MIP-1α and YKL-40 in serum and cerebrospinal fluid of children with mycoplasma pneumonia are increased. The combined detection of MIP-1α and YKL-40 can be used as serum markers to predict encephalitis in children with mycoplasma pneumonia.