The present invention relates to a multistage series microreactor and a fluid mixing method. The microreactor includes a base internally etched with a fluid passage, the base being provided with a fluid inlet and a fluid outlet which are communicated with the fluid passage, where the fluid passage includes a plurality of micro mixing tanks, a jet port is formed at an inlet of the micro mixing tank, adjacent micro mixing tanks are connected by jet port at a contraction section, and a splayed flow baffle plate and a flow splitting column which are arranged corresponding to the jet port are provided in the micro mixing tank, the flow splitting column being arranged below the splayed flow baffle plate. By means of a jet manner, a fluid to be mixed in the invention can be continuously split, compounded, stretched and crushed, thereby realizing rapid mixing and efficient, continuous reaction.

A fluid flow conduit comprises a flow-shaping element shaped to control the velocity distribution of fluid flowing therethrough. A conduit body is shaped to define a longitudinally oriented interior flow region. The flow-shaping element comprises a flow-shaping channel shaped to provide a first curved channel portion curved about a longitudinal axis in a first angular direction to impart angular momentum about the longitudinal axis in the first angular direction on fluid flow therethrough. The flow-shaping channel may be shaped to provide a second curved channel portion that is curved about the longitudinal axis in a second angular direction (opposed to the first angular direction) to impart angular momentum about the longitudinal axis in the second angular direction on fluid flow therethrough. The flow-shaping channel may be shaped to provide one or more slits that communicate fluid between the first and second curved channel portions and a central bore portion.