As an important component of nano-technology and medical technology，nano drug has continuously attracted enormous interest from all over the world both in academic and industrial fields. Engineering and application of pharmaceutical nanoparticles is the primary focus of numerous research groups. This paper summarized the basic principles and preparation methods of nano-/micro-structured drug particles，and reviewed DFT calculation results of pharmaceutical conformers，as well as the academic and industrial achievements of preparing nano-/micro-structured drug particles via liquid-phase precipitation method by authors’research group. For different characteristics of drug systems，anti-solvent，reaction，anti-solvent coupled reaction precipitation，and molecular self-assembly precipitation method were successfully developed for the preparation of nano-/microstructured drug particles. The industrial applications of high-gravity controlled precipitation technology in the preparation of nano drug were also addressed.