The total ionizing dose (TID) response of bulk Si PMOS FinFETs with two fin widths and two types of fin orientation (standard and 45 degrees rotated) is experimentally investigated under four irradiation bias conditions. The bias dependence of bulk Si PMOS FinFETs is demonstrated. The ON-bias configuration is found to be the worst irradiation bias condition. Besides, fin width dependence is illustrated. Narrow fin devices show larger threshold voltage (V-th) shift after irradiation compared with wide fin devices. Furthermore, the fin orientation dependence of the TID response of bulk Si PMOS FinFETs is investigated. The 45 degrees rotated transistors (< 100 > Fin) illustrate smaller irradiation-induced V-th shift and transconductance (g(m)) decrease compared with standard transistors (< 110 > Fin). This orientation dependence is attributed to the oxidation rate and carrier mobility dependence of fin orientation. The results may deepen the understanding of the TID effect of bulk Si PMOS FinFET and offer an idea for future radiation-hardened FinFET integrated circuit (IC) fabrication.