A 3×3 mode division multiplexing communication experimental system is built based on the pattern selectivity of photonic lantern pattern mode multiplexer/demultiplexer. The structural diagram and the operating principle of the system are given. With an intensity modulation and direct detection system, the transmission of 3×4.25 Gbit/s pseudo-random signal in 10 km few-mode fiber is achieved when we use the transmission channels of LP01, LP11a and LP11b modes as the separate channels. The waveforms, eye diagrams and bit error ratio of the received signal are measured. Results show that when the received signal power is -19.1 dBm, -15.8 dBm, -16.6 dBm respectively, the bit error rate of LP01, LP11a and LP11b modes can reach 10-3.