In order to achieve the safety of the preparation process of ultrafine zirconium （Zr） powder， a method for preparing core-shell Zr powder by continuous flow at microscale was studied. A continuous microfluidic system consisting of microfluidic unit and spray-drying unit was established to verify the feasibility. The system can realize the microscale mixing of components， the formation of core-shell structure and the post-processing of samples continuously. Using Zr powder and nitrocellulose （NC） as composite components， the structure regulation of Zr@NC was studied by controlling content of NC and adjusting dry gas pressure at the microscale. In addition， the activity and safety of Zr@NC were analyzed by thermal analysis and electrostatic spark sensitivity test. The results show that the Zr powder with uniform morphology and core-shell structure can be prepared by the continuous microfluidic system. Thermal analysis results show that the oxidation weight gain of Zr@NC is only 1.04% lower than that of the raw Zr， and the energy release is faster. According to the electrostatic spark sensitivity test， it was found that the 50% ignition energy of Zr@NC is increased from 1.42 mJ to 197.82 mJ compared with the raw Zr， which means the electrostatic spark sensitivity is greatly reduced.