Embodiments of the present invention disclose a low dropout regulator, a method for improving stability of the low dropout regulator, and a phase-locked loop. The low dropout regulator includes: a reference voltage source, an error amplifier, a regulating circuit, a load, a first compensation circuit, and a second compensation circuit. The first compensation circuit is coupled to the regulating circuit, and is configured to regulate a dominant pole and a secondary dominant pole of the low dropout regulator, to regulate a phase margin. The second compensation circuit is configured to: decrease the dominant pole of the low dropout regulator and further increase the secondary dominant pole on the basis that the first compensation circuit has regulated the dominant pole and the secondary dominant pole of the low dropout regulator, so as to regulate the phase margin; and regulate a gain-bandwidth product of the low dropout regulator.