The pathological mechanism of childhood asthma is complex, and timely diagnosis is the key to effective prevention and control of childhood asthma. We collected 170 serum samples from 95 children with asthma and 75 healthy children. Serum miRNA biomarkers were analyzed by Illumina sequencing for childhood asthma. Differentially serum miRNAs were confirmed with quantitative reverse transcription polymerase chain reaction (qRT-PCR) assay. The Illumina sequencing data showed the differential expression of 111 serum miRNAs among asthmatic and healthy children. After confirmation of miRNAs expression through qRT-PCR, four of them (namely hsa-miR-106a-5p, hsa-miR-18a-5p, hsa-miR-144-3p, and hsa-miR-375) manifested significant differential expression between asthmatic children and healthy controls. The biomarkers classification tree model created with these four miRNAs using the Biomarker Patterns Software could effectively separate childhood asthma and healthy children, with a specificity of 88.3%, a sensitivity of 95.0%, and an area under the curve (AUC) value of 0.942. The regulatory networks containing miRNAs and their gene targets suggested that the four miRNAs might have gene targets implicated in inflammation, immunity, and transcriptional efficiency. Taken together, this four-serum-miRNA panel is a promising biomarker to diagnose childhood asthma noninvasively.