In2S3 thin films have been prepared on heated glass substrates by ultrasonic spray pyrolysis method. Structure, surface morphology and properties of films with different S/In ratios have been investigated. XRD analysis demonstrated that as-prepared In2S3 thin films have a preferential orientation along the (220) direction and no other phases are observed. Uniformity, density, crystallinity of films were significantly affected by S/In ratios, which influence photoelectric properties of the films. In2S3 thin film is close to standard stoichiometric composition when S/In ratio is 2. Optical transmittance of films is over 90% in the visible region and its energy band gap come up to 2.46eV.