Abstract:Based on the meteorological data from 113 surface and 24 radiosonde stations in Northwest China from 1960 to 2015, the empirical formula was established between precipitable water (PWV) and surface vapor pressure, and the PWV in Northwest China was calculated. With the methods such as inverse distance weighted, Mann Kendall test and Morlet wavelets, the temporal and spatial distribution of PWV and its relations with other meteorological elements were analyzed. The results showed that PWV has increased in last 56 years with the increasing rate of 0.11 mm per decade, and the obviously unimodal types can be examined for the monthly variations. The high PWV area is mainly in the east of Northwest China, and the middle area of Northwest China usually presents a low value. The PWV in most parts of Northwest China has increased, which is obvious in southern Shaanxi, southeastern Gansu, northwestern Qinghai and Xinjiang. The annual average PWV in Northwest China shows an obvious mutation around 1983 and a periodical change with primary period of approximately 4 years. PWV in Northwest China shows a positive correlation with mean air temperature and relative humidity, and a negative correlation with wind speed.