The flow field of pulsing air separation is normally in an unsteady turbulence state. With the application of the basic principles of multiphase turbulent flows, we established the dynamical computational model, which shows a remarkable variation of the unstable pulsing air flow field. CFD (computational fluid dynamics) was used to conduct the numerical simulation of the actual geometric model of the classifier. The inside velocity of the flowing fields was analyzed later. The simulation results indicate that the designed structure of the active pulsing air classifier provided a favorable environment for the separation of the particles with different physical characters by density. We shot the movement behaviors of the typical tracer grains in the active pulsing flow field using a high speed dynamic camera. The displacement and velocity curves of the particles in the continuous impulse periods were then analyzed. The experimental results indicate that the effective separation by density of the particles with the same settling velocity and different ranges of the density and particle size can be achieved in the active pulsing airflow field. The experimental results provide an agreement with the simulation results.