Polyvinyl alcohol (PVA), polyethylene (PE) and ethylene-vinyl acetate copolymer (EVA) film was prepared. The optic capability, infrared transmittance and heat preservation capability of the films were studied respectively. The result indicated that the haze degree of the PVA film decreased about 15% and 12% than PE film and EVA film; PVA film transmittance of IR was more or less than other films in the 7～14 μm wavelength range so that the temperature of greenhouse could be increased effectively in daylight. It was just 16.2% about 20% less than EVA film, and 50% less than PE film. The PVA film could be used as agricultural film in greenhouse to promote heat preservation performance greatly.