The outbreak and intensity of regional storm in the middle reaches of Huanghe River is closely related to the low latitude synoptic system (especially typhoon). The regional storm pro-cess in middle reaches of Huanghe River during June to Sept in 1982-1991 has been investigated. As the regional storm appeared,the space-structure characteristics of moisture source,transportioon,convergence and divergence influenced by the interaction of middle and low latitude synoptic systems were analysed. It is shown that 75 Percent moisture of regional storm and upwards precipitation stems from typhoon,and the moisture source is located bellow 700hpa. The moisture channel center is maitained over 850hpa. The key factors of the regional storm and hard rain are the input capacity of low-level moisture. The movement direction of the moisture channel center is identical with the low-level southeast jet. Otherwise,the presence of the lower surface moisture forced divergence in the south and southeast of the storm region is benefit to the moist ture re-convergence towards the storm region.