Nonlinear optics is given increasing interest due to its wide applications in the area of laser technology, information processing and data storage technology. This paper mainly reviews our researches on the enhanced optical nonlinearity in nano- and micro-crystallized glasses. Utilizing the surface plasmon resonance of noble metal nanoparticles, we realized the enhancement of third order optical nonlinear coefficient through the controlled deposition of oriented Ag nanorods within the oxide glasses or through Ag ion implantation into the chalcohalide glasses. Furthermore, mainly based on the large interface effect, we further realized the enhancement of second order nonlinear optical coefficient through the incorporation of nano-sized Sb2S3, or CdS semiconductor crystals into silica and silicate glasses. Finally, stable second harmonic generation can be obtained together with the little changed transparency utilizing the controllable nucleation and crystal growth of CdGa2S4, AgGeGaS4 and other infrared double-frequency crystals in chalcogenide glasses. (c) 2013 Elsevier B.V. All rights reserved.