The Bi2S3 microcrystallites doped thin film with a significant quantum size effects has been successivelly prepared by the sol-gel process from the hydrolysis of a complex solution of Si (OC2H5 )4, Bi (NO3 )3. 5H2O and SC (NH2)2. The room temperature optical transmission spectra of the films heat-treated at 500℃ for 0～120min show the evidence of quantum size effects as the red-shift of the transmission valley with longer heating time. The optical second harmonic generation.(SHG) was also observed using a Nd:YAG colliding mode locked laser with the maxium intensity of 104 W/cm2.