Abstract Pt-GaAs Schottky barrier APDs have been investigated. The devices were fabricated on GaAs epitaxial layer with carrier concentration of 0.5-3×1015cm-3 and thickness of about 20 μm. Guard ring along with sensitive area was formed by H+ bombardment with energy of 500 keV and dosage of 1×1015cm-2 to prevent edge breakdown. Semi-transparem Pt film was evaporated using a special evaporation source. The peak response wavelength of the device is 8600Å -8835Å at different bias voltages. Optical absopdon edge could extended to 9700Å . Franz-Keldysh effect has been observed. The multiplication of above 100 could reach. Dark current is about several nA. Excess noise coefficient is 7 and both rise and fall time were less than 1 ns. The device could be integrated monolithically and planarly with GaAs FET.