The thermosensitive poly(N-isopropylacrylamide) (PNIPAAm) polymers are stimuli-responsive materials, and throe thermosensitive polymers which exhibit lower critical solution temperature(LCST) in the solution can occur the abrupt nature of the phase transitions at about 32℃. So they can be widely applied in many fields. For example, nanoparticles or microgels composed of the PNIPAAm can be used as the carriers of chugs to control the drugs releasing to cure some disease in the bio-medical engineering. Some PNIPAAm materials can improve the activity of catalysts when those are used as the supports of catalysts. And when the PNIPAAm polymers are bending with some active biological materials, they can be used to separate and purify some biology materials such as proteins, enzymes and amylese. In recent years, many researchers have focused on the applications of the thermosensitive PNIPAAm polymers in many fields, so this paper reviews that these thermosensifive polymers have been applied in these fields.