In this study, composite films of PbS nanoparticles and PANI were used. The PbS/PANI samples were analyzed using XRD, UV-visible, FT-IR and TEM. Furthermore, the effects of PbSNPs on their optical, structural and thermal parameter were determined using DTA, UV-Visible and XRD. The UV and XRD confirmed the successful synthesis of PbS/PANI Nanocomposite. The TEM indicated homogeneous dispersion of PbS in PANI with average diameter of particle is 20nm. Besides, the broadness and reduction of PANI in XRD peaks intensity with increasing PbS is attributed to the intermolecular interactions of PANI and PbS and indicates the successful incorporation of PbS in PANI. The thermal stability was enhanced at different weight percentages of PbS nanoparticle indicated in DTA analysis. The structural changes in the Pbs nanocomposite observed in the XRD.