Pulsating fluidization has the advantages of high level contact of gas-solid and good mass and heat transfer. This paper presents the studies on two types of binary particles: identical sizes but different densities, and identical densities but different sizes. The experiments were carried out in a two dimensional fluidized bed which was made of plexiglas with the size of 200mm (length)×20mm (width) ×1000mm (height). Two air streams, steady flow and pulsating flow, were introduced into the fluidized bed to compare their effects on the mixing of particles. Experiments also investigated the mixing characteristics in different pulse intermittencies in terms of Ashton mixing index and the distribution of jetsam concentration. The results show that pulsating flows imposed on conventional fluidization can improve particle mixing at a lower average gas velocity. It is also found that the Ashton mixing index of equal densities binary mixtures is about 18% bigger than that of unequal densities binary mixtures. Thus the effect of density difference on particle mixing is more significant than the influence of size difference for binary particles.