Abstract: The silicon nitride coatings, a good anti-reflective film to significantly reduce reflection of light from solar cells, were synthesized by pulsed laser deposition (PLD) on Si substrate.The influence of the deposition conditions, including the substrate temperature, laser repetition rate and target/substrate separation, on the microstructures and refractive index of the SiN coatings was investigated in orthogonal experiment and with X-ray diffraction, scanning electron microscopy and ellipsometry.The results show that the substrate temperature and laser repetition rate had a major impact.For example, as the temperature increased from 250℃ to 400℃, the refractive index increased from 1.78 to 2.47; as the laser repetition rate increased from 1 to 4 Hz, the refractive index increased from 1.98 to 2.30.Deposited at 350℃ and 3 Hz, the SiN coatings had an optimized refractive index of 2.2.