【Objective】To predict the functional mechanism and clinical significance of highly expressed maternal embryonic leucine zipper kinase（MELK）in lung adenocarcinoma and lung squamous cell carcinoma by bioinformatics.【Methods】The chip data set GSE7670 was obtained from the Gene Expression Omnibus（GEO）database and combined with the TCGA lung adenocarcinoma（LUAD）and lung squamous cell carcinoma（LUSC）database for differential analysis，and to screen out differential kinases（P < 0.05）. GO biological function enrichment and KEGG pathway analysis of these kinases were performed. Based on String，a protein interaction network was obtained. MCODE plug-in of Cytoscape was applied to find key node proteins and then MELK kinase protein was picked out. MELK expression was analyzed through Oncomine database. Clinical information from TCGA database was obtained，and the relationship between MELK expression and clinicopathological characteristics，prognosis of LUAD and LUSC was analyzed. GeneMANIA was used to predict the function of MELK，and then to verify related co-expressed genes with GEPIA2.【Results】A total of 159 differential kinases were screened out，which were closely related to cell proliferation，apoptosis and various signal pathways. Twentyone important genes were identified by analyzing protein interaction networks. MELK level was higher in male， young or advanced clinical stage lung adenocarcinoma and lung squamous cell carcinoma. The patients with high MELK levels had a shorter progression-free survival（PFS）and overall survival（OS）in LUAD，but there was no significant difference in LUSC. MELK was involved in G2/M transition possibly and was co-expressed with proliferation-related genes（MKI67，PCNA，CCNB1，MCM2，and TOP2A）in LUAD and LUSC.【Conclusions】MELK is highly expressed in LUAD and LUSC. MELK may be involved in the occurrence and development of LUAD by promoting cell mitosis and G2/M transition. MELK could be a new biomarker for LUAD.