This study proposed a new and facile technique to prepare transparent nanofiber reinforced film and evaluated light transmittance and mechanical properties of the film and film application as the temperature monitor. The technique used electrospinning composite solution and heating precursor composite nanofibrous film to package nanofibrous network with the resin. The results showed that the film with at least 90% light transmittance was facilely prepared by the technique. While when the concentration of polyacrylonitrile in the electrospun solution was 12 wt%, heating temperature was 200 degrees C and heating time was 10 min, transparent film with above 95% light transmittance was developed, and showed desirable mechanical properties with the stress of 32.5 Mpa, strain of 51% and Young's modulus of 180 Mpa. Based on the fact that the transparent film changed the color with the temperature, the film showed a promising application as temperature monitor. POLYM. ENG. SCI., 58:1905-1910, 2018. (c) 2017 Society of Plastics Engineers