The invention provides an apparatus for on-line detection of particle properties during fluidized-bed granulation. The apparatus comprises a hermetic shell, a sample acquisition mechanism, a first visual inspection unit, a second visual inspection unit and an image processing system, wherein the first visual inspection unit comprises a first camera, a circular tray and a pressure transducer; the image processing system acquires the particle size information of particles from a falling image of a sample and acquires the angle alpha of repose from an image of a sample accumulation; the second visual inspection unit comprises a measuring cylinder, a measuring-cylinder fixing plate, a light source, a vibrating table and a second camera; and the image processing system acquires the apparent density rho of the particles from the image of the sample in the measuring cylinder before starting of the vibrating table and acquires the tap density rho of the particles from the image of the sample in the measuring cylinder during vibration of the vibrating table. The apparatus provided by the invention can realize on-line detection of the particle size distribution, repose angle, apparentdensity, tap density, porosity and Hausner ratio of the particles during fluidized-bed granulation.