Abstract: According to the statistics of safety accidents which occurred in confined space of construction piles in Chongqing from 2011 to 2017, accidents always occur in summer, while the main city and western region in Chongqing are high incidence areas.Taking the “6.22” accident in Tongnan as an example, synthesize the meteorological monitoring data and NCEP/NCAR reanalysis data, concluding the meteorological causes of digging pile accidents as follows: 1) The rainfall penetrates into the soil, reduces the soil ventilation, and carries toxic and harmful gases to the low place; 2) Human bodies feel comfortable in appropriate conditions of temperature and humidity, therefore operators are easy to relax their vigilance; 3) Small wind speed makes toxic and harmful gases easy to accumulate; 4) Cold air raises the surface pressure, toxic and harmful gases are hard to spread.