This article presents a facile method to prepare CdS/SiO2 composite microspheres and their good catalytic properties. In our method, monodispersed SiO2 particles bearing amino groups (–NH2) were synthesized at first and then used as carriers to load nanosized CdS particles to form CdS/SiO2 composite microspheres. With the addition of CdAc2 solution to the SiO2 dispersion, Cd2+ was attracted to the surfaces of the SiO2 particles through coordination interaction, and then thioacetamide was added to the dispersion. By heating, S2− released and reacted with the Cd2+, CdS/SiO2 composite microspheres were obtained accordingly. The photocatalytic properties of the as-prepared composite microspheres were investigated as well. It was found that the composite microspheres have excellent photocatalytic activities for the degradation of dyes comparing with the commercial P-25 TiO2 catalysts. After using and recycling for three times, the photocatalytic performance still remained very well.