The value of detained mass of material is important for researching the dead bed point of fluidized drying. In order to acquire the effect law of structure of opening hole in gas distributor on detained mass of material, the drying processes of detergent suspension liquor were investigated in the inert particle fluidized bed drier. The curves of detained mass of material for drier with vertical-hole distributor and tithed-hole distributor were measured and compared under the same experimental parameters, such as feed volume, diameter of inert particles, gas temperature of entrance, height of static bed, gas rate of entrance, and concentration of material. Based on the result, the relationship data of drier with tilted-hole distributor were determined between the production capacity and the hole ratio of distributor. The results show that the detained mass of material increase with adding the feed volume or concentration of material, and decrease with adding the diameter of inert particles, gas temperature of entrance, height of static bed, or gas rate of entrance. In addition, changing the hole shape of distributor from vertical-hole to tilted-hole and adding the hole ratio of distributor, can help drier reduce the detained mass of material and enhance the production capacity.