© 2022 Taylor & Francis.The transformations of structural and thermal properties of bamboo precursor fiber impregnated with diammonium hydrogen phosphate (DAP), sodium metasilicate, and urea (in brief DAP-SMSU) throughout the oxidative thermal stabilization process were studied. The oxidation of bamboo fiber was performed for different oxidation duration from 40 to 120 minutes at temperatures up to 245°C utilizing a multistep stabilization strategy. X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR) spectroscopy, and scanning electron microscopy (SEM) were utilized to characterize the structure and properties of oxidized bamboo fibers. The outcomes indicate that DAP-SMSU integration greatly influenced enhancing the thermal stability of bamboo fibers. The findings of the XRD analysis revealed that the amorphization process with increasing stabilization time resulted in the loss of crystallinity and in the growing transformation to a significantly cross-linked and cyclized structure. TGA study revealed that DAP-SMSU pretreatment improved thermal stability by forming a growing amount of ladder-like structures comprising aromatic substances. The drop of crystallinity with time was observed by IR spectra, corroborating the results of X-ray diffraction studies. The development of double-bonded C = C was also observed in IR spectra, which was ascribed to the creation of a cross-linked ladder-like structure.