Abstract: Briefly Introdured methods to calculate the boundary roof thickness which can be divided into three main categories：mechanics analysis method，empirical method and mathematical simulation method.Among them，mathematical simulation method can get full account of the slope′s influence on boundary roof.Mathematical simulation method can directly reflect the stress distribution of the boundary roof，and the stability of the roof canbe made by combination with rock properties.A certain mine as an example，the stress distributions of the roof on different thickness were analyzed,and then the suitable thickness of boundary roof was got out.

Key words: Open-pit and underground jointed mining, Boundary roof, High and steep slope, Mathematical simulation method