We proposed a method identifying the firearm from the gunshot sound. The obtained Fourier cosine coefficients of the autocorrelation functions were used as the individual feature for firearm identification. It was found from the experimental results that the gunshot sound can be used to identify the gun under the conditions, the different barrel lengths, and different size of bullets. But the characteristic of features obtained from gunshot sounds still depended on many factors such as wind speed, temperature, sound reflection and reverberation, type and quality of bullet, direction of the firearm, shooting position and the orientation or location of sound recorder. To improve the method of taking such factors into account would be left to the future task.