Acinetobcter baumannii (A. baumannii) is responsible for various nosocomial infections, which is known as clinically important opportunistic pathogen. Therefore, rapid detection of this pathogen is critical to prevent the spread of infection and appropriate treatment [۱]. Various methods have been developed for the detection of A. baumannii, such as Antibody-based assays, bacterial culture, nucleic acid-based assays, biochemical assays and surface-enhanced Raman scattering [۲]. Most of them are accurate but are accompanied by several problems in on-site detection, such as procedures being complicated and cumbersome, time is long, sensitivity is limited, highly sophisticated instruments and expensive, skilled manpower and the cost is high [۲]. Therefore, to combat the aforementioned challenges, there is an urgent need for new powerful tools that are rapid and sensitive with the ability to detect A. baumannii on-site and that can guide the concerned person for taking appropriate control measures. Among various detection techniques, electrochemical methods have been recognized as one of the most promising technologies due to their high sensitivity, fabrication simplicity, accuracy, cost-effectiveness, selectivity, the possibility of mass production and ease of modification [۳]. In the past few years, aptasensors were used for detecting the type of some bacteria [۴].The proposed system was developed by modifying screen-printed carbon electrodes (SPCE) with an MWCNT@Fe۳O۴@SiO۲-Cl nanocomposite and then using a covalent immobilization of an A. baumannii -specific aptamer (Apt) onto the modified electrode surface, and afterward interaction of methylene blue (MB) with the Apt as an electrochemical redox marker. Upon the incubation of the A. baumannii as a target on the proposed aptasensor, the peak current of MB decreased due to the formation of the Apt-A. baumannii complex and the release of MB from the immobilized Apt on thesurface of modified electrode. The suggested aptasensor was demonstrated to be capable of detecting A. baumannii with a linear range of ۱۰.۰ – ۱.۰×۱۰۷ colony-forming unit(CFU) mL−۱ and a detection limit of ۱ CFU mL−۱ (S/N=۳) using differential pulse voltammetry (DPV) technique. The outcomes revealed that the aptasensor exhibited high A. baumannii detection sensitivity, stability, reproducibility, and specificity.