Theory equations and specification equations are currently main methods to calculate wall rock pressure. These equations are created in certain backgrounds, and are applicable in certain ranges, not fit for deep-buried or large span tunnels. Analysis methods combined with actual project are used, and measured data are contrasted with the theoretical results. Common used calculation equations are discussed from the aspects including calculation accuracy, the relationship with buried depth and the relationship with span of underground structure. Revised calculating equation for wall rock pressure of deep-buried and large-span tunnel are put forward, and is proved to be better on the aspects above. It has significance in theory and practice.