In this study, Scanning Electron Microscope (SEM) was used to investigate the morphology of untreated and treated cotton fabric, SEM-EDX and mapping were used to prove the presence of phosphate in treated cotton fabric CF. The antimicrobial study of the untreated and treated CF with fire retardancy phosphorous-polymethylmethacrylate (PMMA)/modified montmorillonite (MMT) nanocomposites with diffferent concentrations was done on unicellular fungi (C. albicans), two types of bacteria (L. monocytogenes and S. aureus) as Gram-positive and on another two types of bacteria (Salmonella sp. and E. coli) as Gram-negative. by measuring the inhibition zone diameter. Antimicrobial effect of treated and untreated CF were applied through disc diffusion method. The results showed a good efficiency of treated CF samples with the most of microorganisms than untreated CF. The antimicrobial activity also showed the highest inhibition zone for treated CF with P3 (7 %) of fire retardant phosphorous-PMMA/modified MMT nanocomposites was recorded against L. monocytogenes and Salmonella sp. Also, the molecular docking simulation was investigated to treated CF which showed that the treated CF had high efficiency than pencelien g against positive bacteria and methicillin against negative bacteria. On the other hand, the treated CF showed high efficiency than fluconazole against candida alibicans.