The invention discloses a method for determining the diameter of a ball mill steel ball based on material layer impact clamping and breaking. According to the particle size d of a brittle particle, the particle stacking density Rho b, the material layer clamping angle alpha and the unit mass energy consumption C0 of material layer particle breakage, the diameter D0 of a medium condensation polymerization layer inside a ball mill and the steel ball density Rho e are substituted into a steel ball diameter computational formula to calculate the suitable diameter of the steel ball. According to the method for determining the diameter of the ball mill steel ball based on material layer impact clamping and breaking, the defects of a traditional empirical formula and a ball radius theoretical formula which are used for calculating the diameter of the steel ball are overcome, the diameter of the steel ball is calculated on the aspects of material layer impact clamping and breaking, and thus the pertinence, the efficiency and the energy utilization ratio of ball mill impact smashing are improved.