In this paper, a few factors affecting the foehn of the east slope of Daxinganling mountainchain in Northeast China in January are discussed by using the two-dimensional atmospheric meso-scale numerical model. The results show. (1) The leading topographic factor resulting in Daxinganling foehn is the east steep slope of Daxinganling mountainchain. The eastern gentle slope further promotes the development of.Daxinganling foehn. And the small-scale redges can be niglected. (2) The large-scale background conditions are essential for Daxinganling foehn forming. The Daxinganling foehn can not occur when the scorer number (N/U) of the largescale background field is too great or too small.