In this work, the microwave absorption property of weather resistive polymer polyvinylbutyral (PVB)-polyainiline (PANI) / PANI nanofiber composite is studied in the X-band (8.2-12.4 GHz) and Ku-band (12.4-18 GHz). The minimum reflection loss (RL) was obtained for PVB-PANI nanofiber (PVBPN) composite with a large band width as compared to PVB-PANI (PVBP) composite. Additionally, the thickness dependent RL was also studied for all the composites. The minimum RL value of PVBPN nanocomposite was found -79 dB (10.4 GHz) for the thickness 2 mm. The surface morphology and dielectrics of the PVBPN nanocomposite was found to be major factor for the obtained minimum RL value. © 2017 IEEE.