Particle segregation was systematically studied in a binary fluidized bed of inner diameter 0.286 m with fine FCC and coarse millet particles as flotsam and jetsam, respectively. Segregation efficiencies of both flotsam and jetsam, axial and radial fraction profiles were studied and analyzed systematically. A new developed horizontal baffle was examined to see its effects on particles segregation. Experimental results showed that the baffle-free bed could only get high-purity flotsam particles at very low gas velocities. However, both nearly pure jetsam and flotsam particles were obtainable at much higher gas velocities after four layers of new baffle are installed. A wider operating range suitable for particle segregation and greater axial fraction gradients were found in the baffled bed, further proving the baffle's effect on promoting particle segregation. This enables the baffled bed to be a promising continuous particle classifier in industry. Further analysis demonstrated that reduced bubble size, improve bubble flow distribution, and suppressed solid mixing are the intrinsic causes.