Abstract: A cold model experimental device of gas-solid loop fluidized bed in large scale was set up based on the equipments involved in petroleum refining technology, and comparison study of a compound and conventional gas-solid loop fluidized beds in both global and local flow characteristics was carried out. Results show that under the same superficial gas velocities at draft tube and annulus region, and the same static bed height, for the overall flow characteristics, the average solid hold-up at the draft tube and the annulus region, as well as the total average solid hold-up of these two beds were only slightly different, while particles circulation velocity in the compound bed was higher. For the local flow characteristics in various areas, solid hold-up and particles velocity at the distributor region and draft tube bottom of the compound bed were higher. In the middle part of draft tube, the difference of solid hold-up, particles velocity between these two beds was little; in the upper part of draft tube and gas-solid separating region, solid hold-up was lower and the particles velocity was higher for the compound bed. In the annulus region, the difference of solid hold-up between them was little, while the particles velocity was lower in the compound bed.