A full quantum-mechanical simulation of p-type nanowire Schottky barrier metal oxide silicon field effect transistors (SB-MOSFETs) is performed by solving the three-dimensional Schrodinger and Poisson's equations self-consistently. The non-equilibrium Green's function (NEGF) approach is adopted to treat hole transport, especially quantum tunneling through SB. In this work, p-type nanowire SB-MOSFETs are simulated based on the 3-band k.p method, using the k.p parameters that were tuned by benchmarking against the tight-binding method with sp(3)s* orbitals. The device shows a strong dependence on the transport direction, due to the orientation-sensitive tunneling effective mass and the confinement energy. With regard to the subthreshold slope, the  and  oriented devices with long channel show better performance, but they are more vulnerable to the short channel effects than the  oriented device. The threshold voltage also shows a greater variation in the  and  oriented devices with the decrease of the channel length.