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2008年初我国南方发生了大范围、持续性低温冰冻雨雪天气,冻雨、暴雪灾害属历史罕见,许多地方突破50年记录.本文主要从数值模拟方面讨论了1月25日～2月2日冰冻雨雪最为严重的过程.CWRF数值模式较成功地模拟出与实况基本一致的降水分布、 温度垂直分布特征和地面气温状况,较准确地再现了这次罕见的冰冻雨雪过程.地形敏感性试验表明,横断山脉和南岭山脉及邻近山区对冻雨的形成和维持具有重要影响,这种影响是通过锋区特征的改变来实现的.具体体现在,有地形时,因暖湿空气的抬升和冷空气在近地面的堆积而形成易于产生冻雨的倾斜锋区;无地形情况下,锋区坡度增大,冻雨赖以形成的逆温层结结构遭到破坏,使冻雨(冰冻)灾害区在经历短暂的西进南扩后,很快减弱消失.上述地形的移出还通过对环流特征的改变,使对流层底层偏东气流更有组织,整个回流也更清晰,这对南方大范围的降水强度和强降水落区会产生显著影响,但对整体降水的区域分布没有明显影响.“,”The early year of 2008,a large-scale and sustained low-temperature,freezing rain and snow weather occurred in South of China. The disaster caused by freezing rain and snowstorm was unprecedented,and break 50-year records in many areas. In this paper,mainly,the most severe stages from 25 January to 2 February 2008 are discussed. After successfully simulating the precipitation the surface temperature and vertical distribution of temperature field i.e. reproduction the peculiar severe events by CWRF numeric model,a topographic sensitive test showed,the topography have vital influence on the formation and maintenance of freezing rain,which result from the changes of front characteristics. The inclined backwards front zone will be generated easily because the warm and wet air elevations and cold air accumulation in near surface layer when topography exist. But the slope grade of front will increase and the inversion layer structure which support the freezing will be destroyed without topography,so freezing(frozen) disaster areas will weaken quickly and disappear after short-term expansion into west and south. In addition,the removing of above mountains will change the features of circulation and the easterly airstream in low troposphere will be more organized,the return-flow will also be more clear. These changes have a significant impact on the intensity and region of heavy precipitation in South of China,but have no obvious effects on general precipitation distribution.