As a kind of renewable material that is widely available, paper is applicable in various fields. However, the research on its properties focuses mainly on macro mechanical properties, which ignores the micro theory based on the interface of paper. In essence, paper is a microscopic network made up of interrelated fibers. In this paper, a comprehensive experimental and computational study was conducted on the mechanical properties of the fiber and the fiber network, with consideration given to the impact of microstructure. A beam-spring model was established by using the beam fiber network. Then, simulations were performed on exemplary fiber network samples to demonstrate the impact of fiber microparameters on their mechanical properties, such as the force-elongation curve and strength. It was revealed through mechanical experiments that the tensile strength in the Z-direction (fiber bond strength) had a more significant impact on the properties of paper than the zero spacing tensile index (fiber strength), which is highly consistent with the result of modeling. All the simulation results were validated by performing experimental measurement. Finally, computational insights were gained into the pattern of interfiber bond damage on different fiber microlevels. To sum up, the proposed beam-spring model was demonstrated as applicable to predict the response from the fiber networks of paper materials.