As the key to ensure the stability of the excavation surface and reduce the surface settlement, the earth silo pressure, in most cases, bases its traditional calculation formulas on the deformation and failure of the excavation surface, thus failing to integrate the actual working state of the shield machine and resulting in a noticeable gap between the calculated value and the actual value. In order to obtain the accurate value of the silo pressure, on the basis of a mechanical analysis of the tunnel face, and with the working principle of the shield machine combined together, an improved formula has thus been derived for the silo pressure calculation, followed by a further analysis of the effects of the tunnel buried depth ratio and the tunneling speed of the shield machine on the silo pressure. With Hefei Metro Line 4 as the engineering background, by using the finite element software, the accuracy and applicability of the improved earth silo pressure calculation formula can be verified.