To investigate the epidemiology of ST20 carbapenem-resistant
Klebsiella pneumoniae
(CRKP) in China, and further explore the genomic characteristics of
bla
IMP-4
and
bla
NDM-1
coharboring isolates and plasmid contributions to resistance and fitness. Seven ST20 CRKP isolates were collected nationwide, and antimicrobial susceptibility testing was performed. Antimicrobial resistance genes, virulence genes, and plasmid replicons were identified via whole-genome sequencing, and clonality assessed via core-genome multilocus sequence typing. Furthermore, we found four dual-metallo-β-lactamases (MBL)-harbouring isolates, the gene location was detected by Southern blotting, and plasmid location analysis showed that
bla
IMP-4
was located on a separate plasmid, a self-conjugative fusion plasmid, or the bacterial chromosome. These isolates were subjected to long-read sequencing, the presence of
bla
IMP-4
in different locations was identified by genomic comparison, and transposon units were detected via inverse PCR. We subsequently found that
bla
IMP-4
on the fusion plasmid and bacterial chromosome was formed via intact plasmid recombination by the IS
26
and
ltrA
, respectively, and the circular transposon unit was related to cointegration, however,
bla
IMP-4
in different locations did not affect the gene stability. The
bla
NDM-1
-harbouring plasmid contributed to the increased resistance to β-lactams and shortened survival lag time which was revealed in plasmid cured isolates. In summary, the
K. pneumoniae
ST20 clone is a high-risk resistant clone. With the use of ceftazidime/avibactam, MBL-positive isolates, especially dual-MBL-harbouring isolates, should be given additional attention.