The work aims to seek the method of establishing the constitutive model of EPE and honeycomb paperboard series connection, which can provide reference for establishing the constitutive model of other series connection. The stress-strain curve of EPE and the stress-strain curve of honeycomb paperboard were obtained by static compression tests. Three cubed Bezier curve was used to fit the experimental curves. And according to the fitting curve, the stress-strain curve of EPE and honeycomb paperboard series connection was obtained. The fitting curves of EPE and honeycomb paperboard were in good agreement with their respective test curves. The stress-strain curve of series connection obtained in the same way and the stress-strain curve of series connection calculated based on their constitutive models also had good consistency. The results show that it is feasible to obtain constitutive model of the series connection by the method, which provides a reference basis for cushion packaging design.