Abstract: Nano-sized barium sulfate was prepared by micro-reactor technology with sodium sulphate and barium chloride as raw materials.The influence of operation conditions,uch as concentration of reactants,low rate,eactive temperature,n the particle size of the product were investigated.Experimental results showed that the particle size of barium sulfate reduced with the increasing of concentration and flow rate and with the declining of temperature；The average particle size of barium sulfate changed slowly with the variation of temperature when the temperature was below 60 ℃;he average particle size of prepared nano-sized barium sulfate was 32 nm at the concentration of 0.9 mol/L,low rate of 10 L/h and room temperature,he distribution of particle size was narrow and the particles were ellipsoidal.The particle size of the&nbsp; prepared barium sulfate by stirred tank reactor was 5~7 times larger than that of barium sulfate prepared by micro-reactor.<BR>