Binary blend compatibility of polyacrylonitrile (PAN) and polyvinylpyrrolidone (PVP) was computationally simulated at both molecular and mesoscopic levels in order to provide theoretical support for preparing PAN porous nanofibers from PAN/PVP blends. In molecular simulation, Flory-Huggins interaction parameters were calculated to estimate the blend compatibility, in which PAN and PVP were found to be immiscible. This had been further validated by the mesoscopic simulation in terms of the free energy density，the order parameters, and the mesoscopic morphology. Aligned PAN porous nanofibers were prepared by selectively removing PVP from the PAN/PVP blend nanofibers which was prepared by Magnetic-field-assisted electrospinning (MFAES).