Abstract: In two F1 hybrids，we performed heterosis analysis through field traits survey and transcriptome sequencing of cabbage heads leaves. The result found that among the nine horticultural traits，head weight and main petiole weight showed significant differences between F1 hybrids and their parents，among which the head weight exhibited a high value of MPH（mid-parent heterosis）and HPH（high-parent heterosis）in the two F1 hybrids，which means the yield heterosis is obvious. Four groups of differentially expressed genes（DEGs）were compared through transcriptome analysis of cabbage heads leaves. We found that the number of DEGs between F1 hybrids and paternal lines were significantly higher than that between F1 hybrids and their maternal lines in the same criteria. It means similar gene expression profile between maternal lines and their F1 hybrids or a bigger contribution of maternal lines than paternal lines in the formation process of cabbage heads leaves of F1 hybrids. Besides，the fold change of up-regulated genes were higher than that of down-regulated genes，which implied an important role of up-regulated genes in the formation process of cabbage heads leaves of F1 hybrids. The DEGs were further conducted GO（Gene Ontology），COG（Cluster of Orthologous Groups of proteins），KEGG（Kyoto Encyclopedia of Genes and Genomes）pathway enrichment and alternative splicing analysis. The result found that DEGs are highly involved in growth and development，carbohydrate transport and metabolism，signal transduction and amino acid biosynthesis，transport and metabolism pathways. Seven DEGs were randomly selected to perform qRT-PCR and the result was basically consistent with RNA-seq，demonstrating the reliability of transcriptome data. The DEGs that we screened associated with the formation process of heterosis of cabbage heads leaves，able to provide data support for the subsequent research on the molecular mechanism of cabbage heterosis.

Key words: Brassica oleracea L. var. capitata, heterosis, transcriptome analysis, differentially expressed genes（DEGs）