Abstract: GaN crystal string was deposited on Si （111） substrate by hot-wall chemical vapor deposition. Fourier Transform Infrared Transmission （FTIR） Spectroscopy, Scanning Electron Microscopy （SEM）, Selected Area Electron Diffraction （SAED）, X-Ray Diffraction （XRD） and Photoluminescence （PL） spectroscopy were employed to analyze the composition, surface morphology, structure, and optical property of GaN layer. FTIR pattern shows the main composition of the film is GaN and it contains trifle carbon contamination. SEM images show a crystal string with a diameter of 6μm appears in the uniform film. XRD, SAED patterns reveal that the formed string is single-crystalline hexagonal gallium nitride. New feature is found in PL pattern of the crystal string, which is different from the bulk GaN films.