Abstract: Through circuit-level simulations with high-energy particle incidence, the single event transient (SET) effects of the error amplifier (EA) in the PWM controller of a Boost DC-DC converter sensitive component were investigated. The transmission of SET within the loop was analyzed and simulated, revealing the relationship between the impact of SET on the DC-DC output voltage and the load size. A radiation hardening method based on automatic voltage hold was proposed to address the occurrence of SET at the output terminal of the EA in the PWM control unit of the DC-DC converter. Detection of SET was achieved through sampling and comparing the EA output voltage, followed by maintaining the EA output voltage using the automatic hold circuit to isolate the propagation of SET in the loop, ensuring the stability of the DC-DC output voltage. The proposed method was validated based on a 180nm commercial BCD process. Experimental results show that under the condition of linear energy transfer (LET) value of 100 MeV·cm²/mg for high-energy particles, the DC-DC output voltage jump phenomena caused by negative SET and positive SET generated at the EA output have been effectively mitigated, achieving mitigation capabilities of 96.1% and 87.1%, respectively. In addition, for the hardened EA, there is a 95.5% probability that SET occurring at the output node will not affect the output voltage of the DC-DC converter.