利用常规探测资料和诊断分析方法，对2009年11月9-12日山西大范围持续强降雪天气过程进行了综合分析。结果表明：（1）500 hPa阻塞形势和低空低涡切变线稳定维持，700 hPa西南急流、 850 hPa偏东急流、 850 hPa和925 hPa强偏东北气流等三支强气流稳定维持，地面回流形势与河套倒槽共同强烈发展并稳定维持，是造成此次大范围持续强降雪的重要原因。（2）强降雪出现前，低层中纬度持续有暖湿空气向山西地区输送，暖湿中心强度持续增强；从其水平结构变化看，可将此次过程分为锢囚降雪、 回流降雪、 暖倒槽降雪和持续降温四个阶段，各个阶段降雪特点不同。（3）强降雪区上空垂直热力结构为上冷、 中暖、 下冷，低层冷平流强度为普通暴雪的3倍；对流层中低层持续存在对流性不稳定，不稳定区内存在空气辐散，且持续有暖湿平流输入，导致对流性不稳定及其降水不断增强。（4）此次强降雪天气过程中，山西上空大气可降水量累计达到35~88 mm；随着低层和近地层风场的加强和辐合，大气可降水量不断增加，强降雪也呈现持续增加的趋势。（5）强降雪前及整个强降雪期间，强降雪区上空300 hPa以下为水汽散度通量正值区，其强度在500~600 hPa达到最强，且强度为普通暴雪的6倍，而高层和低层均存在弱的辐散。

A heavy snow occurred in Shanxi Province during 9-12 November 2009 were analyzed based on the observed data. The results show that: (1) There has the block circulation on 500 hPa. The vortex, shear line at low was remain steady. There are three strong air flows such as the southwest jet on 700 hPa, the southeast jet on 850 hPa and strong northeast on 850 hPa and 925 hPa. Reflow on surface and inverse trough in Hetao area develop strongly. (2) The analysis of total temperature advection shows that: There is warm and moisture air at low level transport to Shanxi constantly, and the intensity of center strengthen constantly before heavy snow. From its change of horizontal structure, this process can be divided into four stages, such occlusion snow, reflow snow, warmly inverse trough snow and cool down constantly, and there has different snow characteristic within different stage. (3) Above the heavy snow, there is a vertical thermal structure of cold at high and low level, and warm at middle. There is a center intensity of cold advection at low three times as that of ordinary snow. There is constant convection instability at troposphere low level, air divergence in instable area and warm and moisture advection to import constantly. So convective instability and its rain strengthen constantly. (4) In this process, the atmospheric precipitable water above Shanxi add up to 35~88 mm, and with strengthen and convergence of wind field at low level and near surface, there is an increasing of and strong snow will be amplitude constantly. (5) Diagnosis of vapor divergence flux shows that there is a positive value area under 300 hPa, its intensity reached the strongest on 500~600 hPa, while at high and low level, there is a weak divergence before and during heavy snow.