The work aims to study the deformation mode of corrugated paperboard with different thickness under longitudinal compression and the theoretical model and change trend of plateau stress corresponding to the mode. Longitudinal quasi-static compression was conducted on corrugated paperboard with different thickness to simulate the deformation of corrugated paperboard under compression in actual transportation, establish different theoretical models of plateau stress of corrugated paperboard with different thickness, and evaluate the plateau stress according to the test data. When corrugated paperboard of different thickness was subject to longitudinal compression load, the corrugated paperboard underwent three different deformations, including:the face paper and the corrugated core paper were not separated; the face paper and the core paper were partially separated and the face paper and the core paper were completely separated. For different deformations, the plateau stress changed significantly. And as the thickness of the corrugated paperboard increased, there was more separation, so that the plateau stress was reduced obviously. The increase of the thickness will change the deformation of corrugated paperboard and reduce the plateau stress. Therefore, the plateau stress established with thickness considered has certain guiding significance for the mechanical property evaluation of corrugated paperboard, the size selection of corrugated paperboard cushioning material and the design of corrugated case, etc.