Abstract: Ag₂S nanoparticles with a diameter of 10—50 nm were successfully fabricated at ambient temperature in a TX-100/cyclohexane/hexanol/water inverse microemulsion system in the presence of AgNO₃ as a Ag source,Na₂S·9H₂O as a sulfur source and L-cysteine as the coordinating agent. The factors influencing sizes and morphologies of Ag₂S nanoparticles were studied. The as-obtained Ag₂S nanocrystals exhibit strong absorption in UV region,with an absorption edge at around 290 nm. Compared with that of bulk Ag₂S(1 240 nm),the absorption edge exhibits an obvious blue-shift. The particle sizes and morphologies of Ag₂S nanocrystals could be readily controlled by adjusting the molar ratio of Ag⁺/L-cysteine,the molar ratio of water to surfactant(ω₀) as well as the concentration of reactants.