Using three-dimensional rigid-viscoplastic finite element method (FEM), a coupling multivariable numerical simulation model for steel plate rolling has been established based on the physical metallurgy microstructural evolution rule and experiential equations. The effects of reduction, deformation temperature, and rolling speed on the deformation parameters and microstructure in plate rolling were investigated using the model. After a typical rolling process of steel plate 16Mn is simulated, the strain, temperature, and microstructure distributions are presented, as well as the ferrite grain transformation during the period of cooling. By comparing the calculated ferrite grain sizes with measured ones, the model is validated.