The solid state method was used to prepare ceramic LaFeO3 (LFO) nanoparticles. The solution casting method was employed to create the nanocomposite thick film of this ceramic (as filler) with polyvinyl alcohol (PVA). These films were characterized by x-ray diffraction (XRD) and Fourier transform Infrared (FT-IR) spectroscopy techniques. The XRD technique verifies that our samples are in single phase with orthorhombic crystal structure. Powder X software was used to determine the lattice parameters, which were found to decrease with increase in the doping content. To measure the size of crystallites and strain in the LFO; peak broadening, the Williamson–Hall (W–H) method, and the size-strain approach were used. For all XRD reflection peaks, the physical parameters such as strain, stress, and energy density were calculated using the W–H plot, uniform deformation model (UDM), uniform stress deformation model (USDM), uniform deformation energy density model (UDEDM), and the size-strain plot method (SSP). FT-IR data show finger print function groups associated with this polymer. However slight shifts in these functional groups show the possible coulomb interactions with the ceramic oxygen atom. From this vibrational data, different parameters like force constant (K), the stiffness constant (C11 = C12), bulk modulus (B), rigidity modulus (R), Young’s modulus (Y), Poisson ratio (σ), longitudinal elastic wave velocity (Vl), transverse elastic wave velocity (Vt), mean elastic wave velocity (Vm), Debye temperature (θ*D and θD) and lattice energy (UL) were calculated. The variation in elastic parameters with different doping concentration has been observed and discussed. The various physical parameters obtained from these models were compared and a possible explanation was also proposed.