A two dimensional cold CFB test rig has been established, investigation on horizontal mixing of particles in dense bed has been carried out on this test rig. Mixing model has been used in data reduction,the horizontal miring coefficients of particles in different experimental conditions and in different structures of dense bed have been obtained and compared. By using dimensional analysis, non-dimensionalexpression of experimental condition and mixing coefficient have been obtained. A two dimensional cold CFB test rig has been established, investigation on horizontal mixing of particles in dense bed has been carried out on this rig. Mixing model has been used in data reduction, the horizontal miring coefficients of particles in different experimental conditions and in different structures of dense bed have been obtained and compared. By using dimensional analysis, non-dimensionalexpression of experimental condition and mixing coefficient have been obtained.