Abstract: By dividing loads into the external load and the operational load, this paper presents an effective and comprehensive method to predict the loads of shield tunnel machines during excavation based on a mechanics analysis. The method can be employed to investigate the significant bearings of the geological parameters, the operational parameters and the structural parameters of the cutter head on loads. A mechanical model of the operational load due to the coupling interaction between the cutter head and the soil on an excavation face is established. And the fairly good consistency between the predicted result and the on-site recorded datum from subway projects of Tianjin in China can be achieved. The work provides a useful tool for the load prediction in the design and construction process of shield tunnel machines.