In order to analyze the single-event radiation characteristics of BGR (bandgap reference) under extreme conditions such as space environments, a BGR test chip was designed and implemented in both 65 nm and 28 nm bulk CMOS technologies. Pulse laser single-event simulation experiments were conducted to study its single-event radiation characteristics. The experimental results show that when the pulsed laser energy is sufficiently high, the output voltage of BGR significantly increases after irradiation and the voltage cannot recover after annealing, this indicates that SHD (single-event hard damage) presents in the BGR. Further studies indicate that the bipolar junction transistor in BGR is the sensitive device to induce hard damage. The investigation provides important theoretical references for SHD hardening design of BGR in bulk CMOS technologies.