Abstract: ObjectiveTo evaluate the methodological performance of the susceptibility testing for ceftazidime/ avibactam (CZA) com-bined with aztreonam（ATM) against metallo-β-lactamase （MBL)-producing Enterobacterales，and explore a simple，accurate，andwidely applicable combined susceptibility testing method. MethodsThe carbapenem-resistant Enterobacterales (CRE) isolated from the First Affliated Hospital of Kunming Medical University between December 2022 and December 2023were collected. The suscepti-bility of CZA and ATM was determined by the broth microdilution method, and PCRwas used to detect five carbapenemase genes, in-cludingblaxpc，blapm，blaym，blawp，andblaoxa4s.Thestrainsresistant toCZAandATMandproducingMBLwerescreened.The synergistic effect of CZA combined withATMwas evaluated using the broth microdilution method,and its results served as the gold standard to evaluate the performance of five combined susceptibility testing methods such as the strip stacking,strip crossing,disk stacking，disk diffusion, and broth disk elution. ResultsA total of 416 CRE strains were collected. Among them,38 strains were resistant to both CZA and ATM, and 29 produced MBL. The disk diffusion and broth disk elution methods had the best performance,with 100% of sensitivity，specificity，categoricalagreement(CA)，and reproducibility.The diskstacking method exhibited 71%of sensitivity and 72.7% of CA,with the poorest performance. The strip crossing method outperformed the strip stacking method, with sensitivities of 93% and 85%，and CA of 93.1% and 86.4%，respectively. Both showed excellent repoducibility（(100%). ConclusionThe strip crossing method has better performance and can report the minimum inhibitory concentration （MIC)，making it suitable for guiding clinical medication. The disk difusion method is simple to operate but its results are not easily interpreted,making it suitable for pre-liminaryscreening.Thebrothdisk elutionmethod issimple tooperate andcost-effective,and its results are easilyinterpreted,making it suitable for widespread application in clinical microbiology laboratories.