The investigation of fluid flow in fractured rocks is a key issue in underground engineering. Reservoir sandstones as a case study, three specimens with different roughness using the Brazilian splitting were scanned to get the geometric morphology and aperture distribution, and the fractal dimension was introduced to characterize the fracture roughness. The flow experiments through the rough fractures subjected to different normal stresses were conducted to analyze the influence of the fractal dimension and the contact ratio on the nonlinear flow behavior, proving that the Forchheimer equation could better describe the flow nonlinearity. A modified Bandis model based on the experiments was proposed to calculate the max normal displacement of fracture under different normal stresses. Besides, a new model to forecast the nonlinear coefficient B was developed depending on the fractal dimension and the contact ratio, and a semi-empirical equation was employed to describe the critical Reynolds number. The influence of contact on the seepage path is simulated by COMSOL.