Metal is an important component in building metamaterials. Therefore, it is very important to determine the surface second-order nonlinear susceptibility of metal in the study of metamaterial’s nonlinearity. A high-sensitive spectrometer was used to measure the second harmonic generation and the acquisition signal was calibrated by the Maker fringe of the quartz crystal whose second-order nonlinear susceptibility is known. Experimentally, a femtosecond laser with a wavelength of 800nm was used as the laser source. The second harmonic signals generated from a 35nm-thick gold film prepared by vacuum evaporation were systematically measured under different polarization conditions at incident angles from 10° to 80°. Then three second-order nonlinear susceptibilities of the gold film were determined. The experimental results are in good agreement with the theoretical calculation.