The utility mode provides a strengthened micro reaction device and a micro reaction system for preparing micro-nano powder. The micro reaction system comprises a feeding device, a micro mixing device, the strengthened micro reaction device and a material storing groove; and the strengthened micro reaction device comprises a pipeline and ultrasonic generators, the pipeline is provided with a central passageway the size of which is increased gradually, and the ultrasonic generators are arranged outside the central passageway. In the micro reaction system, mixture and reaction are separated so that the mixture and the reaction are respectively carried out in the micro mixing device and the strengthened micro reaction device; and the micro reaction system has the advantages of fast mixing, strong mass transfer capability, low energy consumption, strong operation controllability, high production efficiency, and stable performance and is easy to amplify and the jamming of a micro reaction passageway and the agglomeration of nano particles are effectively prevented. The strengthened micro reaction device and the micro reaction system are particularly applicable to the industrial production of chemical liquid reaction which has high reaction speed, high requirement on transmission, mass transfer and momentum transfer and can generate solid.