In order to increase the transmission capacity of communication system exponentially, a 3×3 mode division multiplexing experiment platform is constructed using 10 km few-mode optical fiber, the mode conversion and multiplexing are realized by the mode-selective photon lantern, and the modulation and detection process is carried out in the phase modulation-coherent receiving mode, and the effective transmission of the 3×34 Gb/s polarization division multiplexed-quadrature phase shift keying (PDM-QPSK) signal is finally completed. The results show that if the received power of LP01, LP11 and LP21 is not less than -25.32 dBm, the bit error rate can be certainly reduced to less than 10-3.