Statistics and experiments reveal that the mechanical failure of a spherical catalyst under single-particle crushing strength and bulk crushing strength tests are both brittle fracture and the fact that the single particle strength data follow a Weibull distribution. A model is proposed for the packing of spherical particles, which assumes tetrahedral contact and force transmission between the spheres. A deduction from this packing is that the broken percentage of spheres during bulk strength measurement follows the relationship of the Weibull equation. Experimental results confirm this conclusion, which relates the single particle property and the bulk behavior of the packed bed of catalytic materials.