The invention discloses a polarization loop adjustment system suitable for narrowband communication, which includes an intermediate frequency signal source, an intermediate frequency phase detector, a first peak detector, a low-pass filter, a second peak detector, a down converter, a radio frequency synchronization source, First audio amplifier, second audio amplifier, voltage controlled oscillator, power amplifier, comparator, described first peak detector and intermediate frequency phase detector are respectively connected with intermediate frequency signal source, described first peak detector and second The audio amplifier is connected, the second audio amplifier is connected with the power amplifier, the low-pass filter is connected with the intermediate frequency phase detector, the low-pass filter is connected with the first audio amplifier, and the first audio amplifier is connected with the voltage-controlled Oscillation source connection. The present invention prevents the operating bandwidth from being limited by the bandwidth of the phase and amplitude amplifiers through the mutual cooperation among the second peak detector, the audio amplifier, the voltage-controlled oscillator and the power amplifier, so that the polarization loop adjustment system is suitable for narrow-band communication.