The conventional lead azide （Pb（N₃）₂， LA） preparation process has problems such as the risk of self-explosion. Aiming at the above problems， the spin-T microfluidic chip with the characteristics of short diffusion distance， large specific surface area， and continuous reaction was used as a microreactor. And then， the LA primary explosive synthesized by microfluidics was spherically modified by using the flow-focusing droplet chip. The effects of the flow rate， crystal form control agent， and other factors on the product were investigated by SEM， XRD， and DSC. The sensitivity and explosion performance of microfluidic LA， microsphere LA， and powder LA were compared. The results show that by controlling the microfluidic reaction parameters， the particle size of the LA can be effectively controlled， and they were all α-type. After the spheroidization， the impact sensitivity H₅₀ （25.5 cm to 12.1 cm） was significantly improved， but the electrostatic spark E₅₀ （1.98 kV to 2.97 kV） and flame sensitivity L₅₀ （26.3 cm to 16.1 cm） were reduced. At the same time， the detonation pressure was increased （by 63.6%）. It shows that the microfluidic technology was an effective method that can safely prepare and modify the LA primary explosive， which provided an idea for the controllable preparation and regulation of sensitive primers.