Abstract: The influence of inert particles on crystal sized distribution (CSD) in gas-liquid-solid three-phase fluidized crystallization process is studied with potassium chloride solution in a conical fluidized bed. The results show that nature of inert particles,volume concentration, size and shape affect crystal size distribution effectively, with the increase density, size and concentration of inert particles, CSD becomes worse. CSD also becomes worse with the increase of gas flow rate, however, when gas flow rate further increases, CSD will become better and then worse again. Increasing density, size,concentration of inert particles will make the effects of enhancing gas flow rate on CSD less effective, meanwhile the gas flow rate corresponding with the turning point of CSD from worse to better will increase. To inhibit the adverse effects of inert particles on CSD, light, small and low concentration particles should be used.