This experiment aimed to study the deformation and the delamination of cardboard during the creasing process. The creasing process was an important link during production of paper box by cardboard, however, this process was likely to cause paperboard delamination. An orthotropic elastoplastic continuum model was used to describe the mechanical property of each layer of cardboard. A cohesion model was used to describe the bonding and the delamination during creasing. The finite element software Abaqus was used to simulate creasing and the cardboard′s distortion and to forecast influence of creasing on paperboard delamination. According to the simulation results, the creasing process can cause paperboard delamination, which was consistent with the real test. The mechanical model can describe the deformation and the delamination of the cardboard.