Abstract: Based on the characteristic of variable gauge rolling and the definition of forward slip, a forward slip theoretical model was proposed in this article. A finite element model was also established with MARC software. The rolling processes of four different variable gauge strips were numerically simulated at the rolling friction coefficient of 0.08 and 0.1. In addition, the total amount of forward slip was measured by an experimental rolling approach. After comparison and analysis, it is found that there is little difference between the value calculated by theoretical forward slip model and the one simulated by finite element method. The difference is less than 0.005. Differing from stable forward slip in tradition constant thickness rolling, the forward slip fluctuates from 0.02 to 0.10 in the variable gauge rolling process. The increase of reduction rate in the variable gauge zone leads to a higher forward slip. A smaller slope of the variable gauge zone and the low friction coefficient result in a better rolling stability and a smaller fluctuation of forward slip. The experiment of TRB rolling also verifies the accuracy of the theoretical forward slip model for variable gauge rolling. The large tolerance between the measured value and the calculated one in thinning rolling is probably caused by the strain condition of deformation area and the increasing slip tendency.