Abstract: Based on 34 meteorological observatories’daily (from 20:00 p.m. of the day to 20:00 p.m. of the next day) precipitation data in Chongqing from 1981 to 2010, and every 6 hour NCEP/NCAR reanalysis data with spatial resolution 2.5°×2.5°, the authors statistically used synthetic analysis method to study regional blocking rainstorm process in western Chongqing. The results were as follows: (1) the large-scale circulation background that led to regional blocking rainstorm process in western Chongqing was the steady‘two trough and one ridge’type, with the low trough of Lake Baikal and the low trough of the eastward Sichuan Basin having in- phase superposition, the subtropical high extending westward and maintaining stably, and the geopotential height field having the characteristics with‘lower value in the west and higher value in the east’; (2) the water vapor from the south China Sea was transported continuously to the western Chongqing providing favorable moisture condition for the generation and maintenance of the rainstorm process; (3) the temperature and humidity field both changed greatly after the rainstorm process; relatively strong warm advection existed around the rainstorm area before and during the rainstorm process, while obvious cold advection took its place after the process. The constant specific humidity line of 10 g/kg in 700 hPa and 15 g/kg in 850 hPa could be used as forecast reference indexes for the blocking rainstorm in western Chongqing.