A radiation-hardening, wide-input-range bandgap reference is designed based on the study of the degradation mechanism of bandgap reference circuits in radiation environments. The design enables the circuit to operate at higher voltages by establishing internal power rails and uses the fork-finger structure of MOS devices to effectively isolate the Shallow Trench Isolation (STI) region from the active region, thereby hardening the reference core against Total Ionizing Dose (TID). Additionally, a Dynamic Load Tracking (DLT) technique is proposed to address the effects of Single Event Transients (SET) on the reference circuit. The output filtering, pass transistor gate filtering, and DLT technique are all applied to enhance SET resilience. The circuit is designed using a 0.18 μm 40 V BCD process, and simulation results show that the circuit can operate within a voltage range of 6 to 40 V. The PN junction current variation of the forked-finger structure under maximum trapped charge concentration is reduced by 27% compared to that of the single-finger structure, and the SET pulse amplitude is reduced by 80% compared to the non-hardened design.