The sub-plate mantle flow traction has been considered as a major driving force for plate motion; however, the force acting on the overlying plate is difficult to be well constrained. One reason lies in the variable rheological flow laws of mantle rocks, e.g. linear versus power-law rheology, applied in previous studies. Here, systematic numerical models are conducted to evaluate the mantle flow traction under variable rheological, geometrical and kinematic conditions. The results indicate that mantle flow traction with power-law rheology is much lower than that with linear rheology under the same mantle/plate velocity contrast. In addition, the existence of lithospheric root in the overlying plate enhances the mantle flow traction. In a regime with reasonable parameters, the mantle flow traction with power-law rheology is comparable to the ridge push on the order of 1012 N/m, whereas that with linear rheology is comparable to the slab pull of 1013 N/m.