Abstract: The threshold of extreme precipitation in short-time in Shandong province are calculated by traditional ranking method、Zindex method and square root transformation method in this paper, it could be found that the extreme precipitation threshold in central and southeast part of Shandong is higher than other regions, extreme precipitation of 1h and 3h have more occurrence numbers and higher intensity than that of 6h, 12h. Analyzes the evironmental parameters of eight extreme precipitation in recent years which are representative in Shandong, the conclusiones are: The middle and lower layer of the site which had extreme precipitation have high-humidity layer obviously; The low-level southwest jet provides extreme precipitation with abundant water vapor and unstable energy; Atmosphere in a state of flux, K≥37℃, TT≥41℃ and LI<0℃, the atmosphere has a certain accumulation of energy, CAPE≥500J/kg; Has high 0℃ layer height that all above 5km, the high reflectivity value area is below 6km;The clouds have thicker warm-layer which will be improve the efficiency of precipitation.