Landslide and debris flow are very harmful and wide-spread in South Gansu and South Shaanxi District, where is one of the key soil conservation districts in the upper reches of the Yangtze river. It is one of the four biggest districts of our country where landslide and debris flow are concentrate and frequent. Combined with mass measuring and preventing, Longnan first station has carried out some special field measures for landslide and debris flow forecast and warning since 1991. A new way in disaster prevention and reduction has been found based on the mass measuring and preventing. 114 999 people have been protected and ￥1 148 115 property loss has been reduced because of having successfully forecasted and solved 92 landslides and debris flows. The rate of investment and profit is 1∶20.59. Thus stabilized life and production spirits of the masses in endangered and threatened areas. A successful way for disaster prevention and reduction of landslide and debris flow was searched out in South Gansu and South Shaanxi province.