Abstract: The zero-IF receiver has I/Q imbalance in the quadrature mixer circuit, which leads to a sharp decline in the receiver's image rejection capability, and the signal-to-noise ratio and dynamic range of the system are affected. This paper designs a method to calculate and compensate the linear phase imbalance of I/Q signal. ADC sampling and Fourier transform are performed on the demodulated I/Q two-way baseband signals, and then the single-side spectrum is taken to calculate the cross-power spectrum and the phase spectrum of the cross-power spectrum. The three-point method is used for phase unwrapping, the phase compensation is performed according to the unwrapped group delay difference and phase offset, and finally the time domain signal is restored. After testing, the method has good compensation effect, simple implementation, low algorithm complexity and high real-time performance.