The invention relates to a test method for the damage rate of coated fuel particles. The method includes the steps of: selecting the total number of coated fuel particles; heating the coated fuel particles in an air atmosphere, wherein outer dense pyrolytic carbon layers of the coated fuel particles with undamaged barrier bearing layers are oxidized and decomposed to obtain solid particles, at thesame time loose pyrolytic carbon layers, inner dense pyrolytic carbon layers and outer dense pyrolytic carbon layers of the coated fuel particles with damaged barrier bearing layers oxidized and decomposed to obtain semi-hollow particles; calculating a first density of the solid particles and a second density of the semi-hollow particles, selecting a liquid with density between the first densityand the second density, mixing the solid particles and semi-hollow particles with the liquid, and counting the number of semi-hollow particles floating on the liquid surface; and dividing the number of semi-hollow particles by the total number of particles to obtain a particle damage rate. In a word, the detection method provided by the invention is simple and accurate in operation, and can effectively detect the damage rate of the barrier bearing layers in the coated fuel particles.