Aiming at the problem of poor noise of conventional low dropout linear regulator (LDO) with a capacitor, a low noise LDO circuit with foldback current-limit protection was designed in a 180 nm BCD process. A first-order RC low-pass filter was inserted between the reference and the error amplifier (EA) to eliminate the high-frequency noise of the reference output and to cancel the feedback resistance in the traditional LDO circuit to reduce its contribution to the noise. The functions of current limiting and foldback were realized by the foldback current-limit protection circuit, and the reasonable setting of the short-circuit current could effectively prevent the LDO from entering the locked state during the startup or recovery process. The simulation result shows that LDO stably outputs 2 V when the input voltage is 4-5 V, the maximum load is 70 mA, and the over-current limit is 120 mA. In a typical case, the noise power spectrum is 12.7 nV/Hz at 1 kHz, and the RMS noise is 3.6 μV.