本文采用传统排序法、Z指数法、平方根变换法分别计算山东省短时极端强降水阈值，发现鲁中和鲁东南极端强降水阈值高于其他区域，其中1、3h极端强降水出现的次数明显多于6、12h的次数，而且降水强度更大。选择近年发生在山东且具有一定代表性的8次极端强降雨天气过程，分析其环境参数，得出结论：发生极端强降水的站点中层和下层存在明显的高湿层；低空急流为极端强降雨提供了丰富的水汽和不稳定能量；大气处于不稳定状态，K指数≥37℃，总指数TT≥41℃，抬升指数LI＜0℃，大气具有一定的能量积累，CAPE≥500 J/kg；具有较高的0℃层高度，0℃层高度都在5km以上；反射率因子高值区基本处于6km以下，云体存在较厚的暖层，利于降水效率的提高。

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.