Hierarchical CdS microspheres self-assembled by nanowires were synthesized via an ethylenediamine tetraacetate assisted solvothermal approach using cadmium chloride and L-cysteine as reaction agents. The phase structure, morphology, and optical properties of the products were investigated by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, and electro-chemiluminescence, respectively. Studies showed that the final morphology of the products was strongly influenced by the concentration of ethylenediamine tetraacetate and reaction temperature. The as-prepared hierarchical CdS spheres could be a good candidate for a detective technology due to its high electro-chemiluminescence intensity.