The invention relates to a rapid and refined value obtaining method for surface mine side slope rock mass joint dimensions based on three-dimensional laser scanning. A three-dimensional laser scanningmeasurement method is adopted for obtaining geometric parameters of structural surfaces, the structural surfaces are divided into groups by utilizing a K-means clustering method, and on the basis oftrace length statistical analysis of all the structural surface groups, a field site measurement result is combined, statistical distribution rules of occurrences and dimensions of structural surfacesof all the rock masses of a side slope as well as a statistical characteristic value are determined, and penetration rate coefficient of the structural surfaces is calculated. The invention providesa rapid and refined value obtaining method for the surface mine side slope rock mass joint dimensions.