The invention discloses a quadrature amplitude modulation (QAM) light vector signal production and distance heterodyne detection device. The device is composed of a sending device and a receiving device. On the sending side, a first Mach Zehnder modulator (MZM) modulates laser and microwave vibrating source and outputs an upper sideband light signal and a lower sideband light signal. The upper sideband light signal passes through a fiber bragg grating, and the lower sideband light signal passes through an optical band pass filter. Digital baseband signals are divided into two channels and are output by a vector waveform generator. A light modulation device modulates the upper sideband light signal output by the fiber bragg grating and outputs a QAM light signal with digital baseband information. A second optical coupler couples the lower sideband light signal and the QAM light signal into the optical fiber. According to the device, a QAM light signal within the range of light frequency domain is transferred into an expected electronic frequency domain by means of distance heterodyne, and an electromagnetic wave with original QAM signal is produced by an antenna. Therefore, the device can be applied to produce high-frequency millimeter waves, and the device has the advantages of simple implementation structure and low consumption.