Two- and three-dimensional (2D and 3D) micro/nanostructures of CdS-polymer nanocomposites have been successfully patterned, combining photopolymerization via a laser four-beam interference technique with in situ synthesis of CdS nanoparticles in the patterned polymer matrix. The morphology and optical properties of CdS nanoparticles in polymer matrices have been confirmed using TEM, XRD, FTIR, UV-vis absorption and fluorescence spectroscopy. Laser irradiation time and film thickness are certified to be the key factors for the control of the micro/nanostructures. With thickening film, the fabricated microstructures of CdS-polymer nanocomposites were dramatically changed from 2D rods to 3D networks which were composed of nanofibres, nanometre-scale walls and micrometre-scale rods. These kinds of 2D and 3D micro/nanostructures could be expected as potential applications in the development of nanotechnology, such as nanomedical systems, micro-fluidic chips, nanoreactors and micro/nanopurification or separation systems.