To study the self-stability of coal pillars under deep conditions, this article focuses on the engineering practice of constructing long-distance inclined tunnel in coal mines using shield tunneling method in Shenhua Xinjie mining area. The study found that the coal pillar can be divided into elastic core zone and marginal plastic zone due to the difference of stress characteristics in different regions. On this basis, a cusp-catastrophe model of coal pillar was deduced, and the formula for determining the instability of the coal pillar has been derived, then the stable state of deep coal pillars during mining was analyzed through numerical calculation (UDEC). The experimental results indicate that as the mining energy of the coal layer slowly releases, the 120m coal pillar gradually yields from the edge to the interior, and a 4.5m plastic zone appears on one side. After calculation, the coal pillar in this project can maintain stability under deep mining conditions, and the research results provide a reference for the reasonable retention of coal pillars in similar projects.