A novel approach to transmit two vector signals based on IQ modulation and coherent detection by using a single photon carrier is proposed and demonstrated.The same polarization state light of single photon carrier carries IQ modulation signal,and the optical carrier with an orthogonal polarization state directly modulated transmission of optical wave through the optical wave.At the receiver,the two orthogonally polarized light waves are separated and sent to a coherent detector.The performance of the transmission is evaluated when the transmission of two QPSK signals with a data rate of 1 Gbps is implemented over a 25 km single-mode fiber.