To investigate the mechanical properties of composite paperboard at different strain rates, quasi-static and dynamic tensile tests were carried out by universal material testing machine and high-speed testing machine. Meanwhile, the tensile failure process and strain field were recorded by using high-speed camera and digital image correlation (DIC) method. The test results reveal that the mechanical properties and failure mechanism of paperboard show significant strain rate dependence. With the increase of strain rate, the tensile strength of the studied material increases significantly, and the fracture strain also shows obvious strain rate dependence at intermediate strain rate. By comparing the test results with the fitting results of the three models of strain rate dependence ratio, the characterization model based on Cowper-Symonds equation can well describe the strain rate dependence of composite paperboard at low and intermediate strain rates. The proposed model can be used not only for the simulation and theoretical research on the energy absorption performance of thin-walled paper tube, but also for the design of impact protection structure.