A multi-channel MIT system based on fully synchronous phase detection is described. The fully synchronous phase detection can further decrease the phase noise at a fast speed. The maximal absolute phase noise of the phase detection circuits is under 0.008 degree within one hour. The system phase error is blow 0.01 degree. The time of one phase detection is about 1 ms. Preliminary imaging results on low conductivity objects (0.25 S/m and 0.5 S/m) are obtained.