Silver sulfide nanocrystals were successfully prepared by γ irradiation in water and ethanol systems, respectively, at an ambient pressure and room temperature. Sodium thiosulfate, thiourea and carbon disulfide were employed as the sulfur ion source. The products were characterized by some means including X ray powder diffraction(XRD) , transmission electron microscopy(TEM) and X ray photoelectron energy spectrum(XPS). The result of the experiments indicated that the kind of the solvent and the sulfur ion source had influence on the size of silver sulfide nanoparticles. An interesting phenomenon was found in the TEM image of sampleⅡ: several long rods existed in the product and a tubular structure could be seen in one of these rods. The formation of this kind of special structure could be relevant to the coordination between thiourea and silver in water system.