Cubic-phase cadmium sulfide (CdS) nanoparticles were formulated through dropwise precipitation. XRD analysis shows that the CdS has an average nanocrystallite size of approximately 3.36 nm. FTIR results reveals that a strong band appeared around 600 cm-1 is due to Cd-S bonds. SEM image demonstrates that many tiny spherical nanoparticles are homogeneously distributed on the sample surface. The CdS nanoparticles show a prominent UV-Vis absorption peak at 506 nm with a direct band gap of 2.24 eV. CdS nanoparticles has induced remarkable photobleaching effect on the highly stable R6G dye solution under UV illumination, which is applicable for future wastewater treatment.