Abstract The movement process of superfine powder extinguishing agent would be affected by temperature gradient, hot smoke and thermal radiation existed in fire. Numerical simulation was used to make a comparative research on superfine powder extinguishing agent movement released in non-fire room and fire room. The results showed that when superfine powder extinguishing agent was released in non-fire room, particles were mainly controlled by drive gas and moved to the bottom of the fire room firstly. And then particles moved to the side walls of the room after they impacted the bottom. Finally, total flooding condition was formed from the bottom to top. When fire was located at the middle ground, particles moved to both sides of the room at early time after release. And then particles reached the flame region from the sides and top of the flame. Finally total flooding condition was formed from the top to the bottom, and the total flooding time was pretty much exactly the same as non-fire condition. When fire was located at the left bottom corner, particles were mainly controlled by eddies, which led to irregular trajectory and uneven concentration distribution of particles. Under this condition, particles were mainly entrained into flame region by eddies, and it took more time to form total flooding condition.