Covellite-type CuS nanocrystals were synthesized by precipitate method from copper (II) nitrate and ammonium sulfide, followed by further thermal treatment at 105°C for 8h in air. The prepared samples were characterized by X-ray diffraction, scanning electron microscopy. The results showed that the single crystalline phase of covellite-type CuS was obtained with average size of nanocrystals 70 nm. The effects of preparative parameters, namely, precipitation pH value, temperature of precipitation, molar ratio of Cu2+/S2- on structure and particle size of covellite-type CuS nanocrystals were also investigated and discussed.