In order to reveal the crack and destabilization evolvement laws of hard rock pillars under dynamic excavation，taking typical iron deposit as physical prototype，the large scale model experiment was carried out using VIC–3D strain measurement equipment of non-contact and in-plane and stress monitoring system and acoustic emission. The results of research indicate that multiple superimposed damages will occur in pillars during excavation of adjacent stopes in horizontal and vertical directions，the barrier pillars and central top pillar of first layer are damaged seriously and show a higher degree of degradation of mechanical properties. On the basis of the analysis of evolution characteristics of pillar damage，large deformation，instability collapse at different stages and based on the compressive arch theory，the destabilization evolution mode of pillars failure was established. Pillars are in low damage stages during the early excavation，which belongs to stable intermittent period. The increase of pillar damages leads to instability falling of barrier and top pillar，which belongs to bursting period. Pillar damages and instability were key factors causing the collapse of goaf，so the displacement，acoustic emission and stress monitoring methods should be used to monitor the severely damaged area，and effective control measures should be taken before the failure period of the pillars.