Abstract: Nanometer semiconductors are an important class of nanometer materials. Electronic and photonic componets of nanometer scale will become the core of micro－electronic and photo－electronic devices of the next generation. The newest advances in semiconductor nanometer material research are reviewed, covering four parts: self－assembled growth of quantum dots, nanometer crystals, microcavity and photonic crystals, and spin electronics. The research on semiconductor nanometer materials that began in this century is the continuation of research on semiconductor superlattices and quantum wells in the last century, while at the same time it has opened up new fields such as single electron electronics, single photon photonics, microcavity and photonic crystals, diluted magnetic semiconductors, and coherent transport of spin electrons. These studies will lay the foundation for developing and fabricating new devices based on new principles, and for realizing quantum computation and communication.