The study of compaction deformation and void evolution of crushed rock body is of great significance to the stability control of the mining area, the safe exploitation of resources and the prevention and control of geological disasters. This paper takes the crushed rock body in the collapse zone of 10806 integrated mining face in Erhai Mine as the research object, adopts indoor physical simulation method, and carries out uniaxial compression test of different grain size grades (0-2cm, 2-4cm, 4-6cm, 6-8cm, 8-10cm and mixed grades) by means of electro-hydraulic servo universal testing machine combined with acoustic emission monitoring system, so as to investigate the compaction and deformation characteristics and void evolution law of the crushed rock body in the collapse zone systematically. The uniaxial compression test systematically investigated the compaction and deformation characteristics of the fractured rock body in the collapse zone and the void evolution law. The study shows that the compression process of the fractured rock body can be divided into a rapid compression stage (loading time <400s) and a slowing down stage (400s-900s), and the compression volume in the initial stage accounts for more than 74% of the total deformation, with the porosity decreasing by 30%-39%. The particle size gradation significantly affected the compression characteristics: the compression of coarse particles (8-10 cm) was 34%-51% higher than that of fine particles (0-2 cm) due to fewer contact points and lower frictional resistance; the porosity of mixed gradation (0-10 cm) was stabilised at 25% by pore filling of fine particles, which was 6% lower than that of a single coarse particle group. The acoustic emission monitoring shows that, except for the 0-2cm group, the acoustic emission energy of the other groups shows a trend of ‘rising and then falling’, which corresponds to the friction-dominated mechanism between the particle crushing in the fast compacting stage and the slow compacting stage. The research results reveal the nonlinear correlation of ‘particle size-compression-porosity’ and the acoustic emission damage evolution mechanism of the fractured rock body, which provides a theoretical basis for the selection of the timing and stability control of the slurry filling in the mining area.