This paper presents a low-noise, high-voltage, high-output-current power operational amplifier designed in a SMIC 180 nm BCD process. The architecture features a low-noise PMOS input stage, a voltage gain stage, and a Class AB output stage biased by a transconductance linear loop. Stability is ensured by Cascode frequency compensation, while integrated hysteretic over-temperature and current-limiting circuits provide robust protection against thermal and electrical damage. Combining 60V DMOS and 1.8V CMOS devices, the amplifier operates over a wide supply range of ±4V to ±30V and a temperature range of -55°C to +125°C. Simulation results demonstrate an equivalent input voltage noise of 8.85 nV/√Hz, a 400mA output current, 143.3dB DC gain, a 6.804 MHz unity-gain bandwidth, a 33.7 V/μs slew rate, with the chip area of 1.79 × 1.12 mm². The proposed amplifier is well-suited for vehicle electronic applications including precision battery sensing, sensor interfaces, and power device driving.