To get low-perm reservoir deeply explored, Stimulated Reservoir Volume has been introduced to China and gets a new name “Volume Fracturing”. As a new technique, rarely is its flowing seepage mechanism studied. This article tries to propose a basic model for volumetric fractured vertical well, which is based on petro physics and Cinco-Ley model. Firstly, the flow underground is parted with two sections----reservoir seepage flow and fracture seepage flow. Then the seepage within reservoir is studied with Green Source function and supposition theory, while the seepage within fracture is assumed as one-dimensional Darcy flow. Finally, the two sections are coupled at the fracture surface with equivalent pressure or flow rates. The pressure and pressure derivative type curve is obtained by solving flow matrix equations, and the influencing factors are also analyzed. To the end, this new model is justified to be an efficient model coupling vertical well, finite fracture and radial composite reservoir, which turns to be a foundation for pressure transient analysis of volume fracturing wells.