AbstractPhytic acid (IP6) as the major phosphorus‐containing component of certain plants, such as cereal, oil plant, and bean possesses strong capability of coordinating with metal ion to form complex salt. In this study, low concentration IP6 was utilized in combination with Al3+ ion to in situ form insoluble Al3+‐IP6 complex salt on the surface of the fabric through coordination driven layer‐by‐layer deposition technology without high temperature cure step, which is an attempt to provide a facile bio‐based flame retardant finishing to polyamide (PA) 66 fabric. Surface structure of the treated PA fabric has been analyzed via ATR‐FTIR and SEM characterization. Effect of BLs' number on the flame retardancy and burning behavior of the treated sample has been examined by the limiting oxygen index (LOI) test, the vertical burning test, microcalorimetry, and thermogravimetric analysis. The results show that 20LBL PA fabric has the highest LOI value, highest residual char yield, and lowest THR value in all the samples and no melt dripping behavior could be detected during combustion of 20LBL PA fabric. Moreover, the insolubility of Al3+‐IP6 salt from the surface could promote the durability of the treated fabric after laundering procedure using water single. This is the first time to use coordination driven layer‐by‐layer deposition technology in the fabric's flame retardant finishing.