The axial solid concentration distributions were measured by using pressure inspection instrument in a 286 mm I.D.and 7 m height burned-oil-sand fluidized bed of wide size distribution.The change trend of axial solid concentration distributions were investigated under different superficial gas velocities，particle size and particle density.The results showed that the burned-oil-sand particles had a wide size distribution，and there was difference in densities and particle sizes for burned-oil-sand particles obtained in different regions and buried depth.The axial average solid concentrations were indicated the whole characteristics of dense in bottom and dilute in top，and kept consistent when bed height was above the transport disengaging height（TDH).With increasing superficial gas velocity，the solid concentrations in dense region decreased，but increased in dilute region.The burned-oil-sand particles whose particle size and particle density were smaller had good fluidization quality.According to the analysis of experimental results，a model of index was established in order to associate with experimental data.It was concluded that the empirical formula can reflect well the law of axial particle concentration distributions under different factors.