The invention provides a method and a piece of equipment for determining the separating efficiency of a separator. The method comprises the following steps: solid particles separated by a separator are collected; particle size analysis is performed on the collected solid particles; the characteristic parameter of the collected solid particles is calculated according to a particle size analysis result, wherein the characteristic parameter is a numerical value representing the particle size and the particle size uniformity of the solid particles; and the separating efficiency corresponding to the characteristic parameter of the collected solid particles is determined according to the pre-established corresponding relationship between the characteristic parameter and the separation efficiency, and the separating efficiency is determined as the separating efficiency of the separator. Difficulty existing in direct measurement on the concentration of material at an inlet and an outlet of the separator is avoided, interference to the equipment itself is very small, the test operation is simple, and the repeatability is good.