Abstract: To improve the compaction properties of granular backfilling materials in western mining area,this paper an- alyzed the relationship between micro-parameters and macroscopic-strain of granular backfilling materials using the methods of scanning electron microscopy,image processing and particle flow numerical simulation. By selecting six in- dicators such as the equivalent grain size of particles,particle shape coefficient,the degree of particle orientation,ap- parent porosity,connectivity rate and grain contact relations,the morphological characteristics,pore characteristics and contact characteristics of granular backfilling materials were quantitatively analyzed. Through PFC numerical simula- tion,the relationship between micro parameters and the compaction properties of granular backfilling materials was dis- cussed,and the result shows that the friction coefficients and the porosity of particles are the main control parameters of the macroscopic strain of granular backfilling materials. From the perspective of reducing the porosity of backfilling ma- terials and increasing the friction of backfilling materials,the granular backfilling materials in western mining area were optimized on the basis of its meso structure and the optimized granular backfilling materials were used in the 3101 working face of Changxing coal mine,the result indicates that the maximum displacement of surface is 15 mm,the maximum horizontal deformation is 0. 8 mm / m,and the surface subsidence is controlled effectively.