Nanomaterial science has attracted a great deal of attention owing to their great potential applications that traditional material cannot work out. In the past decades, scientists have utilized nanomaterials in fields of optics, magnetics and improving the quality of raw materials. Microchannel reactor has amazing performance for preparation of nanoparticles attributes to its high efficiency of micro mixing. Due to the small volume of the channel, the microchannel reactor could provide a homogeneous environment for the reaction system. It ensures that the nucleation and growth of all the particles are homogeneous which results in narrow size distribution. Moreover we can easily control the residence time by changing the channel length to vary the growth time. We can briefly synthesize nanoparticles through the microchannel without any additive agents, which makes the system an environmentally friendly and cost-effective process. This virtue can help for producing ultra-fine drug particles that have strictly restrictions of purity. The continuous synthesis in the microchannel reactor was a simple and efficient way to prepare composite particles. It can change the traditional intermission process to continuous process, which would highly improve the producing efficiency and reduce the labor intention. Neutralization's time constant is orders of magnitude shorter than that for mixing; mixing is rate-determining, and neutralization depends entirely on the rate of mixing. Neutralization synthesis of BaSO4 from 1.0 mol/L Na2SO4 and 1.0 mol/L BaCl2 solutions was carried out using a microchannel reactor with inner diameter of 0.2 mm. The size and morphology of particles were characterized by transmission electron microscope (TEM) images. The results show that spherical nanoparticles have a narrow size distribution from 15nm to 20nm. To offer turbulent flow for the system, we set the flow rate at 20ml/min, which suggest high quantum yield ability for industry production.