Nano-emulsion was successfully prepared by applying microreactor system in water/polyethylene glycol dodecyl ether/dodecane system by the phase inversion temperature method. Nano-emulsification was carried out by combining two consecutive microreactors. The droplet diameter slightly increased from 90 to 120 nm with the elapse of time. The noble estimation procedure was confirmed to design the suitable microreactor for nano-emulsification by the phase inversion temperature method. The results highlight the great potential for continuously preparing the monodispersed nano-emulsion. This is an abstract of a paper presented at the 2007 AIChE Annual Meeting (Salt Lake City, UT 11/4-9/2007).