Objective In this study, a strain of colistin and tigecycline-resistant bacteria isolated in 2009 was analyzed, and the structure of drug-resistant plasmid and genetic environment were discussed, so as to provide basis for the prevention and control of multidrug-resistant bacteria. Methods A strain (GZ12244) with positive mcr and tet(M) was obtained by screening colistin and tigecycline resistance genes. Vitek-2 was used for strain identification, and the drug sensitivity test was carried out by broth dilution method. The molecular typing, drug resistance genes, insertion sequences, plasmid structure and genetic background were analyzed by genome-wide sequencing and bioinformatics. Results Strain GZ12244 is Klebsiella pneumoniae, which is resistant to colistin B, tigecycline, cefuroxime and tetracycline, and carries a variety of drug-resistant related genes such as mcr-1 and tet(M), and some of the drug-resistant genes with antibiotic efflux and antibiotic target change have amino acid substitution mutations. Mcr-1 and tet(M) coexist in a plasmid, and mcr-1 flanked by two insertion sequences ISApl1. There are insertion sequences such as IS15, IS1D and ISEc63 in the upstream and downstream of tet(M) gene. Conclusion Klebsiella pneumoniae GZ12244 is a multidrug-resistant strain. The drug-resistant gene exists in plasmid, and the mobile elements in upstream and downstream may spread the drug-resistant gene.