Abstract: This review describes the synthesis and environmental response of poly N-isopropyl acrylamide (PNIPAM) microgels, and the recent progress of the use of multi-responsive microgels as central components of advanced, functional materials. As “smart” materials, they have various，widespread applications. Significant areas of development include the use of microgels as microreactors for templated synthesis of inorganic nanoparticles with predetermined properties, as optically active materials, and as primary units in site-specific and controlled drug delivery systems.