CdS with different morphologies were prepared by simple methods (mainly by water bath) with different solvents, including CdS nanoparticles (CdS-0), CdS nanorods (CdS-1), CdS nanosheets (CdS-2), and CdS nanospheres (CdS-3). The structures and morphologies of as-prepared samples were characterized by XRD, XPS, UV–vis DRS, TEM, and SEM. All the prepared samples were used for the photoreduction of Cr (VI) to characterize the photocatalytic performance. CdS-1 shows the highest photocatalytic efficiency was prepared by simply stirring using ethylenediamine as solvent and thiourea as the sulfur source; 98.4% of Cr (VI) can be reduced to Cr (III) within 25 min. The increased photocatalytic activity can be attributed to the high crystallinity and purity, fast separate efficiency, and migration efficiency of electrons (e−) and holes (h+), as well. This work showed that morphologies and crystallinities have significant impact on the Cr (VI) photoreduction efficiency and introduced a simple method for fabricating samples with different morphologies, which add the knowledge for Cr (VI) reduction. Hoping our work can provide a tendency to fabricate efficient photocatalysis via a simple method.