The glow discharge polymer (GDP) films each with a thickness of about 5 m are deposited by low-pressure plasma polymer apparatus. The GDP films are heat-treated at different tempertures of 280, 300, 320 and 340 ℃ in Ar atmosphere. The influence of heat treatment on the structure of GDP film is characterized by FT-IR. The optical transparency and optical band of GDP film are investigated by UV-VIS spectrum. The results show that with temperature increasing, the relative content of CH3 decreases, while the relative content values of CH2 and CH increase. The H content in GDP film decreases. The optical band gap decreases, and the transmittance in a range of more than 600nm decreases too.