Cu(In,Ga)S 2 nanoparticles were synthesized by a hot-injection method under a low-vacuum ambience, which were printed and annealed with Se vapor for Cu(In,Ga)(S,Se) 2 solar cells. The Cu(In,Ga)S 2 nanoparticles were around 14 nm, and the stable ink was obtained by dispersing the nanoparticles in hexanethiol. The crystallinity of the Cu(In,Ga)(S,Se) 2 films increased with the increase in annealing temperature. Cu(In,Ga)(S,Se) 2 solar cells with KCN etching after annealing showed better photovoltaic properties than KCN etching before annealing and without etching. The best cell was observed at an annealing temperature of 540 ∘ C and KCN etching after annealing; the parameters of this cell were a short-circuit photocurrent density of 27.12 mA/cm 2 , open-circuit voltage of 0.42 V, fill factor of 0.38, and conversion efficiency of 4.3%.