During tandem hot rolling (THR), the rolling force plays an important role in strip shape control, but the influence mechanism of the rolling force on the strip shape is still currently unclear. This paper proposes a novel 3D multi-stand coupled thermo-mechanical finite element (FE) model for the THR developed employing a segmentation modelling strategy and data transfer technologies. This developed FE model has been validated by industrial experiments. Besides, the effects of rolling force on the strip shape (including strip crown and flatness) in the THR have been quantitatively studied. Results show that the strip crown increases with the rolling force at each stand, while the regulation efficiency of rolling force on the strip crown decreases continuously from (Finish stand 1) F1 to (Finish stand 7) F7, which is attributed to the significant increase in strip plastic rigidity from F1 to F7. Furthermore, lateral metal flow and strip plastic rigidity have a coupled effect on the regulation efficiency of rolling force on the strip flatness; more precisely, the regulation efficiency is mainly affected by the lateral metal flow in the upstream stand, while it is mainly influenced by the strip plastic rigidity in the downstream stand. These findings not only throw light on the influence mechanism of rolling force on the strip shape, but also offer a way to control and improve the strip shape by employing reasonable rolling force during industrial production.