Epitaxial single crystal AlN thin films have been obtained on (001) sapphire substrates by helicon sputtering system at growth temperature of 450°C. Surface acoustic wave (SAW) filters were fabricated on AlN/sapphire. The center frequency is 354.2MHz, which corresponds to a phase velocity of 5667 m/s. The insertion loss and sidelobe rejection were about 24.9dB and 11.4dB, respectively. The value of TCF is measured to be -74.9 ppm/°C and -65.76 ppm/°C at 0.4 μm and 1 μm of film thickness, respectively. The temperature coefficient of frequency (TCF) of AlN/sapphire shows proportional to the film thickness. A frequency downshift about 43 KHz was observed when the UV source with the wavelength of around 200nm and 12 mW/cm2 of power density radiates the surface of SAW devices.