The invention discloses an optical fiber adaptive balanced zero-beat measurement system for measuring time-varying phase signals, wherein a first optical fiber beam splitter of the system receives output light of a narrow linewidth continuous laser, a phase-type electro-optic modulator and an amplitude-type optical fiber electro-optic modulator receive two beams of light output by the first optical fiber beam splitter respectively, a first piezoelectric ceramic modulator receives the output light of the phase-type electro-optic modulator, a second piezoelectric ceramic modulator receives the output light of the amplitude-type optical fiber electro-optic modulator, a second optical fiber beam splitter receives the output light of the first piezoelectric ceramic modulator and the second piezoelectric ceramic modulator, a signal converter receives two beams of output light of the second optical fiber beam splitter and output the light after the light is converted into electrical signals and subtracted, a signal generator is respectively connected to the amplitude-type optical fiber electro-optic modulator and a mixer, the signal converter, the mixer, a filter, a first servo feedback device and the phase-type electro-optic modulator are connected sequentially, and the signal converter is further connected to the first piezoelectric ceramic modulator through a second servo feedbackdevice. The optical fiber adaptive balanced zero-beat measurement system for measuring time-varying phase signals can achieve the shot noise limit measurement.