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The widespread use of antibiotics in large-scale livestock production has led to serious antibiotic resistance. <i>Proteus mirabilis</i> is an important pathogenic bacterium on large-scale farms. Chromosomally localized mobilizable genetic elements (genomic islands) and mobile genetic elements (Tn<i>7</i>-like transposons) play an important role in the acquisition and transmission of resistance genes by <i>P. mirabilis</i>. To study the prevalence and resistance characteristics of antibiotic-resistant genomic islands in <i>P. mirabilis</i> of animal origin in China, we performed whole genome sequencing of <i>P. mirabilis</i> isolated from large-scale pig and chicken farms. Three new variants of PmGRI1 (HN31, YN8, and YN9), and a hybrid structure (HN2p) formed by the multidrug-resistant Tn<i>7</i>-like-HN2p transposon and a genomic island PmGRI1-HN2p, were identified from <i>P. mirabilis</i>. All variants underwent homologous recombination mediated by insertion sequence IS<i>26</i>. A genomic rearrangement in the chromosome between the Tn<i>7</i>-like-HN2p transposon and PmGRI1-HN2p occurred in HN2p. The heterozygous structure contained various antimicrobial resistance genes, including three copies of fluoroquinolone resistance gene <i>qnrA1</i> and 16S rRNA methylase gene <i>rmtB</i>, which are rarely found in <i>P. mirabilis</i>. Our results highlight the structural genetic diversity of genomic islands by characterizing the novel variants of PmGRI1 and enrich the research base of multidrug resistance genomic islands.