As LDO (low dropout voltage regulator,LDO)has the advantages of high response speed,small chip area and low output noise,it is suitable for integrating into infrared focal plane readout circuit as the power module. A low noise linear power supply of the LDO structure with buffer and Miller compensation is designed,and a chip is designed by CSMC 0.6 μm CMOS process,and then the circuit is simulated by Hspice software. Simulation results show that the maximum linear adjustment rate is 10 mV/V,the power supply rejection ratio (PSRR)is 50 dB，load current can reach 100 mA when LDO is under 50 kHz,3.3~5 V supply voltage.