Abstract: Aiming at the problem of safe upward mining of the wedge pillar mining area in Datong Mining Area, the stress distribution and plastic zone of the coal pillar before and during the upward mining were analyzed with UDEC numerical simulation software. The results showed that: stress concentration of wedge pillar is induced by mining in lower coal seam. The further evolution of the stress distribution of the coal pillars was caused by upward mining. According to the influence of the mine-induced stress of each coal pillar, it’s divided into the stress reduction zone, the stress rise zone and the stress stability zone. The maximum values of the stress peak and plastic zone distribution range in the ahead mining-induced pillar were obtained as soon as the initial breaking of the main key stratum. The observation of bottom displacement in the residual pillar mining area of Jinhuagong Mine verified the reliability of the research results in this paper.