Copper indium gallium selenide （CIGS） solar cells have been extensively researched for their outstanding performance. Solution-based preparation techniques offer significant potential for large-scale industrialization. CuIn_0.7Ga_0.3S₂ nanoparticles were synthesized at 200 ℃ via a hot injection method. The method maintained the quantity of Cu， In， and Ga of raw materials while precisely controlling the composition of Cu， In， Ga， and S elements by adjusting the volumes of surfactant oleylamine， solvent dibenzyl ether， and coordinating agent 1-octadecanethiol to 80 ml， 4 ml， and 15 ml， respectively. The atomic ratio of the synthesized nanoparticles was 1∶0.688∶0.299∶2.03， corresponding to CuIn_0.688Ga_0.299S_2.03， with the nanoparticles' size ranging from 5 to 20 nm. The nanoparticles were purified and cleaned using organic solvents with different polarity， resulting in stable dispersion of the nanoparticles in toluene， as well as other more environmentally friendly solvents， such as o-xylene and cyclohexane. With these nanoparticle-based inks with different solvents， the copper indium gallium selenide sulfide （CIGSSe） absorber layers and their thin film solar cells were prepared.