Synoptic situations of two intense precipitation processes occurred on 12-14 February 2015 (snow) and on 17-21 May 2015 (rain) in Xinjiang are analyzed using conventional observations and 6-hourly NCEP reanalysis data. Moisture sources and transportation are simulated and studied based on backward trajectories from the HYSPLIT model output. The results show that both cases happened under the conditions of an eastward moving trough at 500 hPa, vortex and cyclone in the middle-low level and divergence in the upper-level troposphere. 2) In the snow case in February 2015, moisture air mainly comes from west Asia and central-Asia. Dry air is originated from west Asia, descends to surface and absorbing moisture from land surface, and contributes much to the snow case. Moisture air coming from southwest central-Asia also plays a role. 3) In the rain case in May 2015, moisture is mainly originated from Kazakhstan. Dry air from southern Kazakhstan goes down to surface and absorbs moisture from land surface, contributes much to the rainfall. Air parcels with high water vapor content originated from east and southeast Kazakhstan also play a part. 4) In general, water vapor mainly comes from surface in winter and spring, which is different from that in summer precipitation processes, when moisture air originates from Arabian Sea.