At the night of July 16, 2005, the synoptic process of mesoscale convective complex (MCC) occurred in the north part of Heilongjiang Province. The severe convective weather phenomena including thunderstorm, tornado, hailstone, gust and heavy rainfall were observed. Two tornados occurred in the north part of Qiqihar within 70 minutes. The MCC is analyzed by using the Dopple radar data, the satellite data of FY2 and other relevant data. The difference is analyzed between MCC and other general heavy rainfall processes in highlatitudes. The result shows that the obvious mesocyclone can be found in the radar echoes of velocity for MCC. The tornado is generated in the developing stage of MCC. The characteristics of physical quantities show that the conditons for vapor and dynamical factors are required to be more critical for MCC than others. The terrain commonly plays an important role in the generation process of MCC in highlatitudes. At the same synoptic situation, the system evolution occurs at the lee side of the mountains.