Abstract: Based on the 0.35 μm process, a high power supply rejection ratio (PSRR) and fast transient response linear LDO was designed.The LDO consists of a power supply voltage pre-regulation module, a reference source module and an error amplifier module.The power supply voltage pre-regulation module reduces the input voltage fluctuation range. Meanwhile, PSRR enhancement circuit is adopted to improve the linear stability of LDO and PSRR.The error amplifier module adopts a differential amplifier circuit with positive feedback gain to improve the gain of the circuit, and at the same time adopts double-loop feedback technology to improve the transient response speed of LDO.Simulation results show that the output voltage is 5 V, the PSRR low frequency is 128 dB, 100 kHz is 60 dB, and the transient response time is about 0.1 μs.