The invention discloses a horizontal rotator dynamic balance detection system without an additional sensor, which is characterized by comprising the following steps: connecting a current sensor with a servo driver for a driving motor of a horizontal rotator, inputting into an FIFO (first-in first-out) unit, buffering data, controlling the start of an FFT (fast fourier transform) processor by judging whether data is prepared or not, and converting the time domain signal into the frequency domain signal by the data through the FFT processor; and obtaining the corresponding amplitude-frequency characteristics and phase-frequency characteristics, wherein the amplitude-frequency characteristics reflect the relationship between the relative mass of the eccentric point and the vibration frequency, and the phase-frequency characteristics reflect the relationship between the relative position of the eccentric point and the vibration frequency, thus the dynamic balance state of the horizontal rotator is obtained. The horizontal rotator dynamic balance detection system without the additional sensor has the advantages of small error, convenience of installation and low cost, thereby being suitable for wide popularization.