The invention belongs to the technical field of numerical simulation of radiation effect and relates to a bipolar-transistor displacement-effect numerical simulation method. The method starts from measured data of bipolar-transistor displacement damage defects after neutron irradiation, a displacement damage defect model is established, and numerical simulation of neutron displacement effect is completed. With the method, physical limitation of neutron displacement effect cannot be reflected completely with an existing minority carrier life method is broken through, association between bipolar-resistor micro electrical characteristics and microscopic displacement damage defects is established at the same time, and effective means can be provided for deep analysis of influence of the displacement damage defects on internal carrier transport process of transistors.