Phytic acid's high-efficiency flame retardant and N-halamine antibacterial were synergistically applied to cotton fibers for durable antibacterial and flame retardancy. Antimicrobial flame retardant structures were characterized by H Nuclear Magnetic Resonance Spectra (NMR) and Fourier Transform Infrared Spectrometer (FT-IR). FT-IR, X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscope (SEM), Thermogravimetric (TG), Vertical Flammability Test (VFT), and Limiting Oxygen Index (LOI) were utilized to test and characterize the prepared cotton fibers. The results showed that the antibacterial flame retardant could be durably grafted on the surface of cotton fibers for a long time, and it still maintained its self-extinguishing property after 50 washing cycles, with an LOI value of 32.2 % and a damaged length of 67 mm. The NCl bond was formed by simple bleaching treatment, which exhibited excellent bacteriostatic effect, and had a significant inhibitory effect on Escherichia coli and Staphylococcus aureus, and chlorine oxide, as an antibacterial factor, could be reactivated after long-term storage and washing. Through the systematic analysis of cone calorimetry and carbon residue, it was concluded that the flame retardant mechanism of antibacterial flame retardant was mainly condensed phase. The results of the physical property analysis of cotton fibers showed that the whiteness, air permeability, flexibility, and other physical properties of cotton fibers had no obvious change, while the hydrophilicity of the finished fibers were enhanced.