Using theconventional meteorological data, NCEP reanalysis data (horizontal resolution 1°×1°), FY2E satellite images and TBB data, the heavy rain process happened on 7 and 8 July 2014 is studied in detail from the meteorological diagnostic analysis angle, which was caused by Northeast Cold Vortex and produced an effect on the northeast of Inner Mongolia. The main results are: (1) The main water vapor were carried by the Low level jet stream. Different regions had different formation mechanisms of heavy rainfall. The Eastern Xingan Meng and Hulun Beir are found to be located at front of trough and nearby the surface warm front in the south of the shear line, where were the high incidence area of severe weather caused by the instability energy release of strong convergence uplifting. However, the heavy rain happed at the southwest of Hulun Beir was closely associated with the germination and development of the cold vortex and the dynamic effect of the ground low pressure system. (2) The distribution of moist potential vorticity (MPV) is of very good instructive significance for heavy rain occurrence and precipitation area. The heavy rainfall occurred in the superimposed region of the area of anomalously dense isopleths of 700 hPa and the area of MPV2 ≥ 0 at 850 hPa. (3) The maximum rainfall intensity appeared 1 or 2 hours behind the minimum TBB, and the maximum TBB and rainfall intensity did not occur in the same time.