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High intramuscular fat content of pigs improves pork quality and increasing intramuscular fat deposition is a long-term goal in the husbandry of pigs reared for meat production. There are significant phenotypic differences between the Ningxiang (NX) pigs (an indigenous Chinese breed) and Large White (LW) pigs (a western, lean-type breed). The present work aimed to gain insight into the longissimus dorsi muscle transcriptome between the two pig breeds. We investigated the molecular basis of these differences by comparing their transcriptome profiles. RNA-seq technology was used to identify the differentially expressed genes (DEGs) in the longissimus dorsi muscle of the NX and LW pigs. We obtained 692 million clean reads using transcriptome sequencing of muscle samples from the two pig breeds. A total of 885 DEGs were identified, including 469 upregulated and 416 downregulated genes in the NX pigs compared with the LW pigs. Using KEGG pathway analysis, it was found that the significant DEGs were mainly enriched in metabolism-related pathways, such as lipid metabolism and biosynthesis, and glucose metabolism or biosynthesis. Quantitative real-time PCR confirmed the differential expression of eight selected DEGs in both pig breeds. qPCR results showed that the RNA-seq results were reliable. Several DEGs were candidate functional genes related to the lipid metabolism, including CD36, LIPE, MCAT, LPIN1, ANGPTL4, PPARD, SCD, INSR, MOGAT, IGF1, AKT2 and JAK2. Our results provide a comprehensive basis for the investigation of the differences in transcriptional regulation of the muscles between divergent phenotypes.