Abstract: In order to deeply analyze the co-action mechanism of ore pillar and filling body， aiming at the point-pillar filling mining technology， the system model of ore pillar and filling body was abstracted， and the mechanical model was constructed by using FLAC3D numerical simulation software. The co-action relationship and bearing mechanism of ore pillar and filling body were comprehensively analyzed from the whole and local perspectives.The results show that the filling body has four effects on the ore pillar， that is， increase the peak strength of the ore pillar， limit the radial displacement of the ore pillar， delay the failure of the ore pillar and strengthen the bearing capacity of the broken ore pillar. Under the action of the filling body， the bearing characteristics of the ore pillar were significantly improved， and the peak strength was increased by 34%.From the perspective of the whole， the mechanical behavior of the filling body in the bearing process of the system was shown as overall support-passive bearing-displacement constraint-joint bearing.The essential reason why the ore pillar becomes the main carrier in the early stage of loading was the difference of elastic modulus between them.From a local point of analysis，in the system，the central ore pillar and filling body interaction， mutual assistance，and in the process of bearing，the load-bearing mechanism has obvious synergism，to keep the whole bearing capacity of the plane， in addition， the stress stat of the filling body and ore pillar at the system height h=75 mm position was significantly higher than that of the system height h= 50 mm position. The above analysis can provide reference for the optimizaiton and design of mine stratified filling mining.

Key words: ore pillar-filling body system, FLAC3D, monitoring points, synergetic bearing