Abstract: The Fourier-based plane wave beamforming methods were developed in Radio Frequency(RF) signal cannot be directly applied to the ultrasonic imaging system using quadrature demodulation.In order to tackle this problem,a Fourier-based plane wave beamforming method is extended to In-phase and Quadrature(IQ) data imaging.According to the spectrum relation between RF and IQ signal,the spectrum remapping function between the demodulated IQ prebeamformed data and the beamformed IQ image is derived.Thus the beamformed image could be directly reconstructed in frequency domain using IQ signal.The performance of the proposed approach was evaluated in terms of resolution and Contrast to Noise Ratio(CNR) using the data published in Plane Wave Imaging Challenge in Medical Ultrasound(PICMUS) in 2016.Numerical simulation and phantom experiment results show that the proposed IQ approach can increase the imaging speed by 4 times with comparable image resolution and CNR.In-vivo experimental results also confirm the validity of the proposed method in real applications.