Abstract： Objective To explore the value of neutrophil-to-lymphocyte ratio (NLR),lactate dehydrogenase (LDH),and interleukin-6 (IL-6) levels in prognostic assessment of children with Mycoplasma pneumoniae pneumonia (MPP).Method A total of 180 children with MPP admitted to Kunming Children's Hospital from September 2020 to February 2021 were selected as the observation group by prospective studies,including 104 ordinary children and 76 severe children,and 60 healthy children who underwent physical examination during the same period were selected as the control group.The levels of NLR,LDH,and IL-6 were compared between the observation group and the control group to evaluate the evaluation value of NLR,LDH,and IL-6 for the severity of MPP in children.According to the prognosis of MPP,the children with MMP were divided into poor prognosis group (n=35) and good prognosis group (n=145).The clinical data,NLR,LDH,and IL-6 levels of MMP children with different prognoses were compared,and the prognostic factors of MPP in children and the correlation between NLR,LDH,IL-6 and Clinical Pulmonary Infection Score (CPIS),white blood cell count (WBC),procalcitonim (PCT),C-reactive protein (CRP) were analyzed.Statistical methods performed by t-test,x2 test,Logistic regression analysis,receiver operating characteristic (ROC) curve analysis and Spearman model analysis.Result The NLR of ordinary and severe children in the observation group and the control group were 1.5±0.3,2.2±0.3 and 1.2±0.2,respectively,and the levels of LDH were (439.8±30.1) U/L,(528.6±35.6) U/L and (125.8±28.9) U/L,respectively,the levels of IL-6 were (18.3±1.3) ng/L,(25.8±2.1) ng/L and (9.5±1.2) ng/L,respectively,and the NLR,LDH,and IL-6 levels in the observation group were higher than those in the control group (NLR:t=10.135,27.514,LDH:t=86.323,103.974,IL-6:t=44.834,84.297,all P<0.05),and the NLR,LDH,and IL-6 levels in the ordinary children of observation group were lower than those in the severe children (NLR:t=20.599,LDH:t=26.252,IL-6:t=48.065,all P<0.05).The area under the curve (AUC) of the combined assessment of NLR,LDH,and IL-6 was the highest,at 0.911,with the sensitivity and specificity of 82.89% and 89.42%,respectively.The CPIS (OR=7.232,95% CI:5.055-10.347),WBC (OR=6.839,95% CI:4.752-9.844),PCT (OR=8.882,95% CI:6.375-12.374),CRP (OR=11.520,95% CI:8.125-16.333),NLR (OR=11.517,95% CI:7.852-16.894),LDH (OR=11.881,95% CI:7.698-18.337),and IL-6 (OR=12.424,95% CI:8.025-19.235) were the independent risk factors for the prognosis of MPP childrenin (all P<0.05).The levels of NLR,LDH and IL-6 in children with MPP were positively correlated with CPIS,WBC,PCT and CRP (all P<0.05).Conclusion The levels of NLR,LDH and IL-6 in children with MPP are significantly increased,which can be used as potential indicators for evaluating the condition and prognosis of MPP.